Strong interactions in many-body quantum systems complicate the interpretation of charge transport in such materials. To shed light on this problem, we study transport in a clean quantum system: ultracold 6Li in a two-dimensional (2D) optical lattice, a testing ground for strong interaction physics in the Fermi-Hubbard model. We determine the diffusion constant by measuring the relaxation of an imposed density modulation and modeling its decay hydrodynamically. The diffusion constant is converted to a resistivity using the Nernst-Einstein relation. That resistivity exhibits a linear temperature dependence and shows no evidence of saturation, two characteristic signatures of a bad metal. The techniques we develop here may be applied to measurements of other transport quantities, including the optical conductivity and thermopower.

1 aBrown, Peter, T.1 aMitra, Debayan1 aGuardado-Sanchez, Elmer1 aNourafkan, Reza1 aReymbaut, Alexis1 aHébert, Charles-David1 aBergeron, Simon1 aTremblay, A.-M., S.1 aKokalj, Jure1 aHuse, David, A.1 aSchauß, Peter1 aBakr, Waseem, S. uhttp://science.sciencemag.org/content/early/2018/12/06/science.aat413400826nas a2200229 4500008004100000245022500041210006900266260000800335300001100343490000700354100002200361700001800383700001400401700001600415700001300431700001600444700002200460700001700482700002400499700001700523856005600540 2018 eng d00aElectronic and magnetic properties of the candidate magnetocaloric-material double perovskites ${\mathrm{La}}_{2}{\mathrm{MnCoO}}_{6}$, ${\mathrm{La}}_{2}{\mathrm{MnNiO}}_{6}$, and ${\mathrm{La}}_{2}{\mathrm{MnFeO}}_{6}$0 aElectronic and magnetic properties of the candidate magnetocalor cSep a1251320 v981 aGauvin-Ndiaye, C.1 aBaker, T., E.1 aKaran, P.1 aMassé, É.1 aBalli, M1 aBrahiti, N.1 aEskandari, M., A.1 aFournier, P.1 aTremblay, A.-M., S.1 aNourafkan, R uhttps://link.aps.org/doi/10.1103/PhysRevB.98.12513200482nas a2200133 4500008004100000245011500041210006900156260000800225300001100233490000700244100001700251700002400268856005600292 2018 eng d00aHall and Faraday effects in interacting multiband systems with arbitrary band topology and spin-orbit coupling0 aHall and Faraday effects in interacting multiband systems with a cOct a1651300 v981 aNourafkan, R1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.98.16513000463nas a2200133 4500008004100000245009600041210006900137260000800206300001100214490000700225100001700232700002400249856005600273 2017 eng d00aEffect of nonsymmorphic space groups on correlation functions in iron-based superconductors0 aEffect of nonsymmorphic space groups on correlation functions in cSep a1251400 v961 aNourafkan, R1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.96.12514000579nas a2200169 4500008004100000245012900041210006900170260000800239300001400247490000700261100001600268700001800284700001400302700001300316700002400329856005600353 2017 eng d00aEffects of interaction strength, doping, and frustration on the antiferromagnetic phase of the two-dimensional Hubbard model0 aEffects of interaction strength doping and frustration on the an cDec a241109(R)0 v961 aFratino, L.1 aCharlebois, M1 aSémon, P1 aSordi, G1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.96.24110900558nas a2200181 4500008004100000245007900041210006900120260000800189300001100197490000700208100001800215700001500233700001400248700001500262700001900277700002400296856005600320 2017 eng d00aHall effect in cuprates with an incommensurate collinear spin-density wave0 aHall effect in cuprates with an incommensurate collinear spinden cNov a2051320 v961 aCharlebois, M1 aVerret, S.1 aFoley, A.1 aSimard, O.1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.96.20513200544nas a2200157 4500008004100000245012200041210006900163260000800232300001100240490000700251100001600258700001700274700001600291700002400307856005500331 2017 eng d00aMaximum entropy analytic continuation for frequency-dependent transport coefficients with nonpositive spectral weight0 aMaximum entropy analytic continuation for frequencydependent tra cMar a1211040 v951 aReymbaut, A1 aGagnon, A -M1 aBergeron, D1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.95.12110400471nas a2200145 4500008004100000245007200041210006900113260000800182300001100190490000700201100001600208700002100224700002400245856005600269 2017 eng d00aOrbital effect of the magnetic field in dynamical mean-field theory0 aOrbital effect of the magnetic field in dynamical meanfield theo cDec a2351350 v961 aAcheche, S.1 aArsenault, L.-F.1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.96.23513500585nas a2200169 4500008004100000245011600041210006900157260000800226300002700234490000700261100001500268700001500283700001800298700001900316700002400335856005600359 2017 eng d00aPhenomenological theories of the low-temperature pseudogap: Hall number, specific heat, and Seebeck coefficient0 aPhenomenological theories of the lowtemperature pseudogap Hall n cSep a125139 Editor's choice0 v961 aVerret, S.1 aSimard, O.1 aCharlebois, M1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.96.12513900553nas a2200169 4500008004100000245010600041210006900147260000800216300001100224490000700235100001600242700001400258700001800272700001300290700002400303856005600327 2017 eng d00aSignatures of the Mott transition in the antiferromagnetic state of the two-dimensional Hubbard model0 aSignatures of the Mott transition in the antiferromagnetic state cJun a2351090 v951 aFratino, L.1 aSémon, P1 aCharlebois, M1 aSordi, G1 aTremblay, A.-M., S. uhttps://link.aps.org/doi/10.1103/PhysRevB.95.23510901484nas a2200157 4500008004100000245008800041210006900129300001100198490000700209520097900216100001401195700001801209700001901227700002401246856005601270 2017 eng d00a{Subgap structures and pseudogap in cuprate superconductors: Role of density waves}0 aSubgap structures and pseudogap in cuprate superconductors Role a0545180 v953 aIn scanning tunneling microscopy conductance curves, the superconducting gap of cuprates is sometimes accompanied by small subgap structures at very low energy. This was documented early on near vortex cores and later at zero magnetic field. Using mean-field toy models of coexisting d-wave superconductivity, d-form-factor density wave, and extended s-wave pair density wave (s PDW), we find agreement with this phenomenon, with s PDW playing a critical role. We explore the high variability of the gap structure with changes in band structure and density wave (DW) wave vector, thus explaining why subgap structures may not be a universal feature in cuprates. In the absence of nesting, nonsuperconducting results never show signs of pseudogap, even for large density wave magnitudes, therefore reinforcing the idea of a distinct origin for the pseudogap, beyond mean-field theory. Therefore, we also briefly consider the effect of DWs on a preexisting pseudogap.

1 aVerret, S1 aCharlebois, M1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/921400527nas a2200193 4500008004100000022001400041245004600055210004500101260001200146300000700158490000700165653001300172653003900185653001100224653001100235100002400246700001700270856004600287 2017 eng d a0304-288X00aTaming High-temperature superconductivity0 aTaming Hightemperature superconductivity c09/2017 a430 v5710aCuprates10aHigh-temperature superconductivity10areview10atheory1 aTremblay, A.-M., S.1 aChubukov, A. uhttp://cerncourier.com/cws/download/Sep1700463nas a2200133 4500008004100000245009200041210006900133260000800202300001100210490000700221100002200228700002400250856005500274 2016 eng d00aAlgorithms for optimized maximum entropy and diagnostic tools for analytic continuation0 aAlgorithms for optimized maximum entropy and diagnostic tools fo cAug a0233030 v941 aBergeron, Dominic1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevE.94.02330300636nas a2200193 4500008004100000245013000041210006900171260000800240300001100248490000700259100001600266700001800282700002000300700001600320700001400336700001300350700002400363856005500387 2016 eng d00aAntagonistic effects of nearest-neighbor repulsion on the superconducting pairing dynamics in the doped Mott insulator regime0 aAntagonistic effects of nearestneighbor repulsion on the superco cOct a1551460 v941 aReymbaut, A1 aCharlebois, M1 aAsiani, Fellous1 aFratino, L.1 aSémon, P1 aSordi, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.94.15514600506nas a2200145 4500008004100000245010800041210006900149260000800218300001100226490000800237100001700245700001500262700002400277856005900301 2016 eng d00aCorrelation-Enhanced Odd-Parity Interorbital Singlet Pairing in the Iron-Pnictide Superconductor LiFeAs0 aCorrelationEnhanced OddParity Interorbital Singlet Pairing in th cSep a1370010 v1171 aNourafkan, R1 aKotliar, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevLett.117.13700100526nas a2200169 4500008004100000245007200041210006900113260000800182300001100190490000700201100001600208700001600224700001800240700001900258700002400277856005500301 2016 eng d00aMott transition and magnetism on the anisotropic triangular lattice0 aMott transition and magnetism on the anisotropic triangular latt cDec a2451330 v941 aAcheche, S.1 aReymbaut, A1 aCharlebois, M1 aSénéchal, D.1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.94.24513301711nas a2200169 4500008004100000022001400041245008900055210006900144300001000213490000600223520112900229100001501358700001401373700001301387700002401400856011701424 2016 eng d a2045-232200a{An organizing principle for two-dimensional strongly correlated superconductivity.}0 aorganizing principle for twodimensional strongly correlated supe a227150 v63 aSuperconductivity in the cuprates exhibits many unusual features. We study the two-dimensional Hubbard model with plaquette dynamical mean-field theory to address these unusual features and relate them to other normal-state phenomena, such as the pseudogap. Previous studies with this method found that upon doping the Mott insulator at low temperature a pseudogap phase appears. The low-temperature transition between that phase and the correlated metal at higher doping is first-order. A series of crossovers emerge along the Widom line extension of that first-order transition in the supercritical region. Here we show that the highly asymmetric dome of the dynamical mean-field superconducting transition temperature , the maximum of the condensation energy as a function of doping, the correlation between maximum and normal-state scattering rate, the change from potential-energy driven to kinetic-energy driven pairing mechanisms can all be understood as remnants of the normal state first-order transition and its associated crossovers that also act as an organizing principle for the superconducting state.

1 aFratino, L1 aSémon, P1 aSordi, G1 aTremblay, A.-M., S. uhttp://www.ncbi.nlm.nih.gov/pubmed/26964524 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC478681100508nas a2200157 4500008004100000245008800041210006900129260001200198300001100210490000700221100001600228700001400244700001300258700002400271856005500295 2016 eng d00aPseudogap and superconductivity in two-dimensional doped charge-transfer insulators0 aPseudogap and superconductivity in twodimensional doped chargetr c06/2016 a2451470 v931 aFratino, L.1 aSémon, P1 aSordi, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.93.24514700554nas a2200157 4500008003900000245010700039210006900146260003500215300001100250490000700261100001200268700002100280700001600301700002400317856005500341 2015 d00aAntiferromagnetism in the Hubbard model on the honeycomb lattice: A two-particle self-consistent study0 aAntiferromagnetism in the Hubbard model on the honeycomb lattice bAmerican Physical SocietycJul a0451110 v921 aArya, S1 aSriluckshmy, P V1 aHassan, S R1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.92.04511100471nas a2200133 4500008003900000245008700039210006900126260003500195300001100230490000600241100001200247700002400259856005400283 2015 d00ad-wave superconductivity in the frustrated two-dimensional periodic Anderson model0 adwave superconductivity in the frustrated twodimensional periodi bAmerican Physical SocietycFeb a0110190 v51 aWu, Wei1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevX.5.01101900588nas a2200157 4500008003900000245013600039210006900175260003500244300001100279490000700290100001800297700001900315700001700334700002400351856005500375 2015 d00aImpurity-induced magnetic moments on the graphene-lattice Hubbard model: An inhomogeneous cluster dynamical mean-field theory study0 aImpurityinduced magnetic moments on the graphenelattice Hubbard bAmerican Physical SocietycJan a0351320 v911 aCharlebois, M1 aSénéchal, D.1 aGagnon, A -M1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.91.03513200516nas a2200145 4500008003900000245009800039210006900137260003500206300001100241490000700252100001600259700001600275700002400291856005500315 2015 d00aMaximum entropy analytic continuation for spectral functions with nonpositive spectral weight0 aMaximum entropy analytic continuation for spectral functions wit bAmerican Physical SocietycAug a0605090 v921 aReymbaut, A1 aBergeron, D1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.92.06050900567nas a2200145 4500008003900000245013400039210006900173260003500242300001100277490000700288100002700295700002000322700002400342856005500366 2015 d00aSuperconducting dome in doped quasi-two-dimensional organic Mott insulators: A paradigm for strongly correlated superconductivity0 aSuperconducting dome in doped quasitwodimensional organic Mott i bAmerican Physical SocietycNov a1951120 v921 aHébert, Charles-David1 aSémon, Patrick1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.92.19511200505nas a2200145 4500008003900000245008700039210006900126260003500195300001100230490000700241100001700248700001500265700002400280856005500304 2014 d00aElectric polarization of S$_{0.5}$Ba$_{0.5}$MnO$_3$: A multiferroic Mott insulator0 aElectric polarization of S 05 Ba 05 MnO3 A multiferroic Mott ins bAmerican Physical SocietycDec a2204050 v901 aNourafkan, R1 aKotliar, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.90.22040500508nas a2200145 4500008003900000245009500039210006900134260003500203300001100238490000700249100001400256700001300270700002400283856005500307 2014 d00aErgodicity of the hybridization-expansion Monte Carlo algorithm for broken-symmetry states0 aErgodicity of the hybridizationexpansion Monte Carlo algorithm f bAmerican Physical SocietycApr a1651130 v891 aSémon, P1 aSordi, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.89.16511300538nas a2200157 4500008003900000245008700039210006900126260003500195300001100230490000700241100001400248700001900262700002000281700002400301856005500325 2014 d00aLazy skip-lists: An algorithm for fast hybridization-expansion quantum Monte Carlo0 aLazy skiplists An algorithm for fast hybridizationexpansion quan bAmerican Physical SocietycAug a0751490 v901 aSémon, P1 aYee, Chuck-Hou1 aHaule, Kristjan1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.90.07514900497nas a2200145 4500008003900000245007900039210006900118260003500187300001100222490000700233100001700240700001500257700002400272856005500296 2014 d00aOrbital magnetization of correlated electrons with arbitrary band topology0 aOrbital magnetization of correlated electrons with arbitrary ban bAmerican Physical SocietycSep a1251320 v901 aNourafkan, R1 aKotliar, G1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.90.12513200487nas a2200133 4500008003900000245010100039210006900140260003500209300001100244490000700255100001200262700002400274856005500298 2014 d00aPhase diagram and Fermi liquid properties of the extended Hubbard model on the honeycomb lattice0 aPhase diagram and Fermi liquid properties of the extended Hubbar bAmerican Physical SocietycMay a2051280 v891 aWu, Wei1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.89.20512800659nas a2200193 4500008004100000245006600041210006600107300001200173490000700185100002400192700002400216700001700240700001500257700001500272700002300287700002300310700001500333856011700348 2014 eng d00aTelegraphic noise in transport through colloidal quantum dots0 aTelegraphic noise in transport through colloidal quantum dots a882-8870 v141 aLachance-Quirion, D1 aTremblay, A.-M., S.1 aLamarre, S A1 aMéthot, V1 aGingras, D1 aCamirand Lemyre, J1 aPioro-Ladrière, M1 aAllen, C N uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84894149742&partnerID=40&md5=5635c4b4bcbd83fb40a95f37de0b0fad00536nas a2200157 4500008003900000245009400039210006900133260003500202300001500237490000700252100001300259700001400272700001300286700002400299856005500323 2013 d00ac-axis resistivity, pseudogap, superconductivity, and Widom line in doped Mott insulators0 acaxis resistivity pseudogap superconductivity and Widom line in bAmerican Physical SocietycJan a041101 (R)0 v871 aSordi, G1 aSémon, P1 aHaule, K1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.87.04110100564nas a2200157 4500008003900000245009200039210006900131260003500200300001100235490000700246100003100253700002300284700002000307700002400327856005500351 2013 d00aEntropy, frustration, and large thermopower of doped Mott insulators on the fcc lattice0 aEntropy frustration and large thermopower of doped Mott insulato bAmerican Physical SocietycJan a0351260 v871 aArsenault, Louis-François1 aShastry, Sriram, B1 aSémon, Patrick1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.87.03512600494nas a2200169 4500008003900000245004400039210004300083260003500126300001100161490000700172100001800179700001600197700001300213700001900226700002400245856005500269 2013 d00aMott p-n junctions in layered materials0 aMott pn junctions in layered materials bAmerican Physical SocietycJan a0351370 v871 aCharlebois, M1 aHassan, S R1 aKaran, R1 aSénéchal, D.1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.87.03513700521nas a2200157 4500008003900000245007300039210006900112260003500181300001100216490000700227100001900234700001500253700001600268700002400284856005500308 2013 d00aResilience of d-wave superconductivity to nearest-neighbor repulsion0 aResilience of dwave superconductivity to nearestneighbor repulsi bAmerican Physical SocietycFeb a0751230 v871 aSénéchal, D.1 aDay, A G R1 aBouliane, V1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.87.07512300687nas a2200217 4500008003900000022002200039245004200061210004200103260004200145490000600187653004000193653001300233653002800246653002400274653002200298100002400320700001800344700001500362700002400377856006800401 2013 d a978-3-89336-884-600aStrongly correlated superconductivity0 aStrongly correlated superconductivity aJülichbVerlag des Forschungszentrum0 v310acluster dynamical mean-field theory10aCuprates10aorganic superconductors10aStrong correlations10aSuperconductivity1 aTremblay, A.-M., S.1 aPavarini, Eva1 aKoch, Erik1 aSchollwöck, Ulrich uhttp://www.cond-mat.de/events/correl13/manuscripts/correl13.pdf00452nas a2200133 4500008003900000245005800039210005800097260003500155300001100190490000700201100003100208700002400239856005500263 2013 d00aTransport functions for hypercubic and Bethe lattices0 aTransport functions for hypercubic and Bethe lattices bAmerican Physical SocietycNov a2051090 v881 aArsenault, Louis-François1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.88.20510900541nas a2200145 4500008003900000245010400039210006900143260003500212300001100247490000700258100003100265700002000296700002400316856005500340 2012 d00aBenchmark of a modified iterated perturbation theory approach on the fcc lattice at strong coupling0 aBenchmark of a modified iterated perturbation theory approach on bAmerican Physical SocietycAug a0851330 v861 aArsenault, Louis-François1 aSémon, Patrick1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.86.08513300633nas a2200169 4500008003900000245013700039210007100176260003500247300001100282490000700293100002200300700002400322700001900346700001900365700002400384856005500408 2012 d00aBreakdown of Fermi liquid behavior at the (π,π)=2k_F spin-density wave quantum-critical point: The case of electron-doped cuprates0 aBreakdown of Fermi liquid behavior at the ππ2kF spindensity wave bAmerican Physical SocietycOct a1551230 v861 aBergeron, Dominic1 aChowdhury, Debanjan1 aPunk, Matthias1 aSachdev, Subir1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevB.86.15512300463nas a2200133 4500008003900000245006900039210006900108260003500177300001100212490000700223100002000230700002400250856005500274 2012 d00aImportance of subleading corrections for the Mott critical point0 aImportance of subleading corrections for the Mott critical point bAmerican Physical SocietycMay a2011010 v851 aSémon, Patrick1 aTremblay, A.-M., S. uhttp://www.physique.usherbrooke.ca/pages/node/801500479nas a2200145 4500008003900000245006700039210006700106260001200173490001100185100001300196700001400209700001300223700002400236856007300260 2012 d00aPseudogap temperature as a Widom line in doped Mott insulators0 aPseudogap temperature as a Widom line in doped Mott insulators c07/20120 v2, 5471 aSordi, G1 aSémon, P1 aHaule, K1 aTremblay, A.-M., S. uhttp://www.nature.com/srep/2012/120731/srep00547/full/srep00547.html00512nas a2200157 4500008003900000245007000039210006800109260003500177300001100212490000800223100001300231700001400244700001300258700002400271856005900295 2012 d00aStrong Coupling Superconductivity, Pseudogap, and Mott Transition0 aStrong Coupling Superconductivity Pseudogap and Mott Transition bAmerican Physical SocietycMay a2164010 v1081 aSordi, G1 aSémon, P1 aHaule, K1 aTremblay, A.-M., S. uhttp://link.aps.org/doi/10.1103/PhysRevLett.108.21640100504nas a2200145 4500008003900000245009100039210006900130260000900199300001600208490000700224100002800231700001900259700002400278856005600302 2011 d00ad-wave superconductivity on the checkerboard Hubbard model at weak and strong coupling0 adwave superconductivity on the checkerboard Hubbard model at wea c2011 a054545/1--80 v841 aChakraborty, Shiladitya1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/757000361nas a2200109 4500008003900000245005900039210005400098260001200152490000700164100002400171856005600195 2011 d00aForeword - "Superconductivity: Advances and Prospects"0 aForeword Superconductivity Advances and Prospects c06/20110 v671 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/742300374nas a2200109 4500008003900000245006600039210006400105300000800169490000700177100002400184856005600208 2011 d00aHigh-Temperature Superconductivity from Short-Range Repulsion0 aHighTemperature Superconductivity from ShortRange Repulsion a1050 v671 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/742500357nas a2200121 4500008003900000245004400039210004300083260001200126300001000138490000700148100002400155856005600179 2011 d00aLa supraconductivité en un clin d'oeil0 aLa supraconductivité en un clin doeil c06/2011 a61-640 v671 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/744700547nas a2200145 4500008003900000245013400039210006900173260003500242300001100277490000700288100001300295700001300308700002400321856005600345 2011 d00aMott physics and first-order transition between two metals in the normal-state phase diagram of the two-dimensional Hubbard model0 aMott physics and firstorder transition between two metals in the bAmerican Physical SocietycAug a0751610 v841 aSordi, G1 aHaule, K1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/749800644nas a2200157 4500008003900000245017800039210006900217260003600286300001600322490000700338100002200345700002100367700001800388700002400406856005600430 2011 d00aOptical and dc conductivity of the two-dimensional Hubbard model in the pseudogap regime and across the antiferromagnetic quantum critical point including vertex corrections0 aOptical and dc conductivity of the twodimensional Hubbard model bAmerican Physical Societyc2011 a085128/1-350 v841 aBergeron, Dominic1 aHankevych, Vasyl1 aKyung, Bumsoo1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/751600422nas a2200133 4500008003900000245006200039210006000101260001200161300000700173490000700180100002100187700002400208856005600232 2011 d00aPréface- La supraconductivité: progrès et perspectives0 aPréface La supraconductivité progrès et perspectives c06/2011 a590 v671 aTaillefer, Louis1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/744900343nas a2200121 4500008003900000245003700039210003600076260001200112300001000124490000700134100002400141856005600165 2011 d00aSuperconductivity in a Nutshell 0 aSuperconductivity in a Nutshell c06/2011 a65-680 v671 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/742400473nas a2200133 4500008003900000020002700039245006400066210006100130490002000191100002400211700002400235700001900259856006100278 2011 d aISBN 978-3-642-21830-900aTwo-Particle-Self-Consistent Approach for the Hubbard Model0 aTwoParticleSelfConsistent Approach for the Hubbard Model0 vSpringer Series1 aTremblay, A.-M., S.1 aMancini, Ferdinando1 aAvella, Adolfo uhttp://www.springer.com/materials/book/978-3-642-21830-901076nas a2200169 4500008004100000245005400041210005400095260000900149300001800158490000700176520059400183100001500777700001900792700001500811700002400826856005600850 2010 eng d00aDynamical electronic nematicity from Mott physics0 aDynamical electronic nematicity from Mott physics c2010 a180511(R)/1-40 v823 aVery large anisotropies in transport quantities have been observed in the presence of very small in-plane structural anisotropy in many strongly correlated electron materials. By studying the two-dimensional Hubbard model with dynamical-mean-field theory for clusters, we show that such large anisotropies can be induced without static stripe order if the interaction is large enough to yield a Mott transition. Anisotropy decreases at large frequency. The maximum effect on conductivity anisotropy occurs in the underdoped regime, as observed in high-temperature superconductors.

1 aOkamoto, S1 aSénéchal, D.1 aCivelli, M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727401104nas a2200157 4500008004100000245008900041210006900130260000900199300001500208490000800223520060900231100001300840700001300853700002400866856005600890 2010 eng d00aFinite Doping Signatures of the Mott Transition in the Two-Dimensional Hubbard Model0 aFinite Doping Signatures of the Mott Transition in the TwoDimens c2010 a226401/1-40 v1043 aExperiments on layered materials call for a study of the influence of short-range spin correlations on the Mott transition. To this end, we solve the cellular dynamical mean-field equations for the Hubbard model on a plaquette with continuous-time quantum Monte Carlo calculations. The normal-state phase diagram as a function of temperature T, interaction strength U, and filling n reveals that upon increasing n towards the insulator, there is a surface of first-order transition between two metals at nonzero doping. For T above the critical end line there is a maximum in scattering rate.

1 aSordi, G1 aHaule, K1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728002161nas a2200145 4500008004100000245011200041210006900153260000900222300001500231490000700246520166800253100001401921700002401935856005601959 2010 eng d00aGeneralized dc and ac Josephson effects in antiferromagnets and in antiferromagnetic d-wave superconductors0 aGeneralized dc and ac Josephson effects in antiferromagnets and c2010 a115102/1-90 v813 aThe Josephson effect is generally described as Cooper-pair tunneling but it can also be understood in a more general context. The dc Josephson effect is the pseudo-Goldstone boson of two coupled systems with a broken continuous Abelian U(1) symmetry. Hence, an analog should exist for systems with broken continuous non-Abelian symmetries. To exhibit the generality of the phenomenon and make predictions from a realistic model, we study tunneling between antiferromagnets and also between antiferromagnetic d-wave superconductors. Performing a calculation analogous to that of Ambegaokar and Baratoff for the Josephson junction, we find an equilibrium current of the staggered magnetization through the junction that, in antiferromagnets, is proportional to s(L)xs(R), where s(L) and s(R) are the Neacuteel vectors on either sides of the junction. Microscopically, this effect exists because of the coherent tunneling of spin-one particle-hole pairs. In the presence of a magnetic field which is different on either sides of the junction, we find an analog of the ac Josephson effect where the angle between Neacuteel vectors depends on time. In the case of antiferromagnetic d-wave superconductors we predict that there is a contribution to the critical current that depends on the antiferromagnetic order and a contribution to the spin-critical current that depends on superconducting order. The latter contributions come from tunneling of the triplet Cooper pair that is necessarily present in the ground state of an antiferromagnetic d-wave superconductor. All these effects appear to leading order in the square of the tunneling matrix elements.

1 aChasse, D1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723401262nas a2200181 4500008004100000245009900041210006900140260000900209300001400218490000700232520069900239100001400938700001300952700001900965700002400984700001601008856005601024 2009 eng d00aFirst-order Mott transition at zero temperature in two dimensions: Variational plaquette study0 aFirstorder Mott transition at zero temperature in two dimensions c2009 a17002/1-60 v853 aThe nature of the metal-insulator Mott transition at zero temperature has been discussed for a number of years. Whether it occurs through a quantum critical point or through a first-order transition is expected to profoundly influence the nature of the finite-temperature phase diagram. In this paper, we study the zero temperature Mott transition in the two-dimensional Hubbard model on the square lattice with the variational cluster approximation. This takes into account the influence of antiferromagnetic short-range correlations. By contrast to single-site dynamical mean-field theory, the transition turns out to be first order even at zero temperature. Copyright (C) EPLA, 2009

1 aBalzer, M1 aKyung, B1 aSénéchal, D.1 aTremblay, A.-M., S.1 aPotthoff, M uhttps://www.physique.usherbrooke.ca/pages/node/722702490nas a2200169 4500008004100000245017200041210006900213260000900282300001600291490000700307520186500314100002002179700001902199700002202218700002402240856005602264 2009 eng d00aLow-energy theory of the t-t '-t ''-U Hubbard model at half-filling: Interaction strengths in cuprate superconductors and an effective spin-only description of La2CuO40 aLowenergy theory of the tt t U Hubbard model at halffilling Inte c2009 a235130/1-220 v793 aSpin-only descriptions of the half-filled one-band Hubbard model are relevant for a wide range of Mott insulators. In addition to the usual Heisenberg exchange, many other types of interactions, including ring exchange, appear in the effective Hamiltonian in the intermediate coupling regime. In order to improve on the quantitative description of magnetic excitations in the insulating antiferromagnetic phase of copper-oxide (cuprate) materials, and to be consistent with band-structure calculations and photoemission experiments on these systems, we include second-and third-neighbor hopping parameters, t' and t", into the Hubbard Hamiltonian. A unitary transformation method is used to find systematically the effective Hamiltonian and any operator in the spin-only representation. The results include all closed four-hop electronic pathways in the canonical transformation. The method generates many ring exchange terms that play an important role in the comparison with experiments on La2CuO4. Performing a spin-wave analysis, we calculate the magnon dispersion as a function of U, t, t', and t". The four parameters are estimated by fitting the magnon dispersion to the experimental results of Coldea et al. [Phys. Rev. Lett. 86, 5377 (2001)] for La2CuO4. The ring exchange terms are found essential, in particular to determine the relative sign of t' and t", with the values found in good agreement with independent theoretical and experimental estimates for other members of the cuprate family. The zero-temperature sublattice magnetization is calculated using these parameters and also found to be in good agreement with the experimental value estimated by Lee et al. [Phys. Rev. B 60, 3643 (1999)]. We find a value of the interaction strength U similar or equal to 8t consistent with Mott insulating behavior.

1 aDelannoy, J Y P1 aGingras, M J P1 aHoldsworth, P C W1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724801357nas a2200181 4500008004100000245011300041210006900154260000900223300001800232490000700250520077900257100001201036700001601048700001501064700001601079700002401095856005601119 2009 eng d00aMixed pairing symmetry in kappa-(BEDT-TTF)(2)X organic superconductors from ultrasonic velocity measurements0 aMixed pairing symmetry in kappaBEDTTTF2X organic superconductors c2009 a220511(R)/1-40 v803 aDiscontinuities in elastic constants are detected at the superconducting transition of layered organic conductors kappa-(BEDT-TTF)(2)X by longitudinal and transverse ultrasonic velocity measurements. Symmetry arguments show that discontinuities in shear elastic constants can be explained in the orthorhombic compound only if the superconducting order parameter has a mixed character that can be of two types, either A(1g)+B-1g or B-2g+B-3g in the classification of irreducible representations of the orthorhombic point group D-2h. Consistency with other measurements suggests that the A(1g)+B-1g(d(xy)+d(z(x+y))) possibility is realized. Such clear symmetry-imposed signatures of mixed order parameters have not been observed in other superconducting compounds.

1 aDion, M1 aFournier, D1 aPoirier, M1 aTruong, K D1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725101231nas a2200157 4500008004100000245006200041210006200103260000900165300001500174490000700189520076500196100001300961700001900974700002400993856005601017 2009 eng d00aPairing dynamics in strongly correlated superconductivity0 aPairing dynamics in strongly correlated superconductivity c2009 a205109/1-80 v803 aConfirmation of the phononic origin of Cooper pair formation in superconductors came with the demonstration that the interaction was retarded and that the corresponding energy scales were associated with phonons. Using cellular dynamical mean-field theory for the two-dimensional Hubbard model, we identify such retardation effects in d-wave pairing and associate the corresponding energy scales with short-range spin fluctuations. We find which frequencies are relevant for pairing as a function of interaction strength and doping and show that the disappearance of superconductivity on the overdoped side coincides with the disappearance of the low-energy feature in the antiferromagnetic fluctuations, as observed in neutron-scattering experiments.

1 aKyung, B1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727002886nas a2200205 4500008004100000245010100041210006900142260000900211300001600220490000700236520226200243100001902505700001302524700001902537700001502556700001402571700001502585700002402600856005602624 2008 eng d00aAnomalous superconductivity and its competition with antiferromagnetism in doped Mott insulators0 aAnomalous superconductivity and its competition with antiferroma c2008 a184516/1-120 v773 aProximity to a Mott insulating phase is likely to be an important physical ingredient of a theory that aims to describe high-temperature superconductivity in the cuprates. Quantum cluster methods are well suited to describe the Mott phase. Hence, as a step toward a quantitative theory of the competition between antiferromagnetism and d-wave superconductivity in the cuprates, we use cellular dynamical mean-field theory to compute zero-temperature properties of the two-dimensional square lattice Hubbard model. The d-wave order parameter is found to scale like the superexchange coupling J for on-site interaction U comparable to or larger than the bandwidth. The order parameter also assumes a dome shape as a function of doping, while, by contrast, the gap in the single-particle density of states decreases monotonically with increasing doping. In the presence of a finite second neighbor hopping t', the zero-temperature phase diagram displays the electron-hole asymmetric competition between antiferromagnetism and superconductivity that is observed experimentally in the cuprates. Adding realistic third neighbor hopping t '' improves the overall agreement with the experimental phase diagram. Since band parameters can vary depending on the specific cuprate considered, the sensitivity of the theoretical phase diagram to band parameters challenges the commonly held assumption that the doping Vs T-c/T-c(max) phase diagram of the cuprates is universal. The calculated angle-resolved photoemission spectrum displays the observed electron-hole asymmetry. The tendency to homogeneous coexistence of the superconducting and antiferromagnetic order parameters is stronger than observed in most experiments but consistent with many theoretical results and with experiments in some layered high-temperature superconductors. Clearly, our calculations reproduce important features of d-wave superconductivity in the cuprates that would otherwise be considered anomalous from the point of view of the standard Bardeen-Cooper-Schrieffer approach. At strong coupling, d-wave superconductivity and antiferromagnetism naturally appear as two equally important competing instabilities of the normal phase of the same underlying Hamiltonian.

1 aKancharla, S S1 aKyung, B1 aSénéchal, D.1 aCivelli, M1 aCapone, M1 aKotliar, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726202331nas a2200157 4500008004100000245010800041210006900149260000900218300001600227490000700243520181200250100001502062700001602077700002402093856005602117 2008 eng d00aCompetition between charge and spin order in the t-U-V extended Hubbard model on the triangular lattice0 aCompetition between charge and spin order in the tUV extended Hu c2008 a214408/1-110 v773 aSeveral new classes of compounds can be modeled in first approximation by electrons on the triangular lattice that interact through on-site repulsion U as well as nearest-neighbor repulsion V. This extended Hubbard model on a triangular lattice has been studied mostly in the strong coupling limit for only a few types of instabilities. Using the extended two-particle self-consistent approach (ETPSC), that is valid at weak to intermediate coupling, we present an unbiased study of the density and interaction dependent crossover diagram for spin- and charge-density wave instabilities of the normal state at arbitrary wave vector. When U dominates over V and electron filling is large, instabilities are chiefly in the spin sector and are controlled mostly by Fermi surface properties. Increasing V eventually leads to charge instabilities. In the latter case, it is mostly the wave vector dependence of the vertex that determines the wave vector of the instability rather than Fermi surface properties. At small filling, nontrivial instabilities appear only beyond the weak coupling limit. There again, charge-density wave instabilities are favored over a wide range of dopings by large V at wave vectors corresponding to root(3) x root(3) superlattice in real space. Commensurate fillings do not play a special role for this instability. Increasing U leads to competition with ferromagnetism. At negative values of U or V, neglecting superconducting fluctuations, one finds that charge instabilities are favored. In general, the crossover diagram presents a rich variety of instabilities. We also show that thermal charge-density wave fluctuations in the renormalized-classical regime can open a pseudogap in the single-particle spectral weight, just as spin or superconducting fluctuations.

1 aDavoudi, B1 aHassan, S R1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724502059nas a2200169 4500008004100000245009500041210006900136260000900205300001500214490000700229520152900236100001601765700001501781700001301796700002401809856005601833 2008 eng d00aConditions for magnetically induced singlet d-wave superconductivity on the square lattice0 aConditions for magnetically induced singlet dwave superconductiv c2008 a094501/1-90 v773 aIt is expected that at weak to intermediate coupling, d-wave superconductivity can be induced by antiferromagnetic fluctuations. However, one needs to clarify the role of Fermi surface topology, density of states, pseudogap, and wave vector of the magnetic fluctuations on the nature and strength of the induced d-wave state. To this end, we study the generalized phase diagram of the two-dimensional half-filled Hubbard model as a function of interaction strength U/t, frustration induced by second-order hopping t'/t, and temperature T/t. In experiment, U/t and t'/t can be controlled by pressure. We use the two-particle self-consistent approach, valid from weak to intermediate coupling. We first calculate as a function of t'/t and U/t the temperature and wave vector at which the spin response function begins to grow exponentially. d-wave superconductivity in a half-filled band can be induced by such magnetic fluctuations at weak to intermediate coupling, but only if they are near commensurate wave vectors and not too close to perfect nesting conditions where the pseudogap becomes detrimental to superconductivity. For given U/t, there is thus an optimal value of frustration t'/t where the superconducting T-c is maximum. The noninteracting density of states plays little role. The symmetry d(x2-y2) vs d(xy) of the superconducting order parameter depends on the wave vector of the underlying magnetic fluctuations in a way that can be understood qualitatively from simple arguments.

1 aHassan, S R1 aDavoudi, B1 aKyung, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726001887nas a2200157 4500008004100000245008500041210006900126260000900195300001600204490000700220520138200227100002101609700001901630700002401649856005601673 2008 eng d00aConvexity of the self-energy functional in the variational cluster approximation0 aConvexity of the selfenergy functional in the variational cluste c2008 a075105/1-120 v773 aIn the variational cluster approximation (VCA) (or variational cluster perturbation theory), widely used to study the Hubbard model, a fundamental problem that renders variational solutions difficult in practice is its known lack of convexity at stationary points, i.e., the physical solutions can be saddle points rather than extrema of the self-energy functional. Here, we suggest two different approaches to construct a convex functional Omega[Sigma]. In the first approach, one can show analytically that in the approximation where the irreducible particle-hole vertex depends only on center of mass coordinates, the functional is convex away from phase transitions in the corresponding channel. Numerical tests on a tractable version of that functional show that convexity can be a nuisance when looking for instabilities both in the pairing and particle-hole channels. Therefore, an alternative phenomenological functional is proposed. Convexity is explicitly enforced only with respect to a restricted set of variables, such as the cluster chemical potential that is known to be otherwise problematic. Numerical tests show that our functional is convex at the physical solutions of VCA and allows second-order phase transitions in the pairing channel as well. This opens the way to the use of more efficient algorithms to find solutions of the VCA equations.

1 aNevidomskyy, A H1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727301837nas a2200169 4500008004100000245009400041210006900135260000900204300001600213490000700229520129500236100002101531700001601552700001901568700002401587856005601611 2008 eng d00aMagnetism and d-wave superconductivity on the half-filled square lattice with frustration0 aMagnetism and dwave superconductivity on the halffilled square l c2008 a064427/1-130 v773 aThe role of frustration and interaction strength on the half-filled Hubbard model is studied on the square lattice with nearest- and next-nearest-neighbor hoppings t and t(') using the variational cluster approximation (VCA). At half-filling, we find two phases with long-range antiferromagnetic (AF) order: the usual Neel phase, stable at small frustration t(')/t, and the so-called collinear (or superantiferromagnet) phase with ordering wave vector (pi,0) or (0,pi), stable for large frustration. These are separated by a phase with no detectable long-range magnetic order. We also find the d-wave superconducting (SC) phase (d(x)(2)-y(2)), which is favored by frustration if it is not too large. Intriguingly, there is a broad region of coexistence where both AF and SC order parameters have nonzero values. In addition, the physics of the metal-insulator transition in the normal state is analyzed. The results obtained with the help of the VCA method are compared with the large-U expansion of the Hubbard model and known results for the frustrated J(1)-J(2) Heisenberg model. These results are relevant for pressure studies of undoped parents of the high-temperature superconductors: we predict that an insulator to d-wave SC transition may appear under pressure.

1 aNevidomskyy, A H1 aScheiber, C1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727200969nas a2200145 4500008004100000245006600041210006400107260000900171300001400180490000700194520053100201100001100732700002400743856005600767 2008 eng d00aScaling and commensurate-incommensurate crossover for the d=20 aScaling and commensurateincommensurate crossover for the d2 c2008 a37013/1-60 v843 a{Quantum critical points exist at zero temperature, yet, experimentally their influence seems to extend over a large part of the phase diagram of systems such as heavy-fermion compounds and high-temperature superconductors. Theoretically, however, it is generally not known over what range of parameters the physics is governed by the quantum critical point. We answer this question for the spin-density wave to Fermi-liquid quantum critical point in the two-dimensional Hubbard model. This problem is in the d = 2

1 aRoy, S1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727701552nas a2200169 4500008004100000245008500041210006900126260000900195300001600204490000700220520103100227100001401258700001501272700001501287700002401302856005601326 2007 eng d00aInteraction-induced adiabatic cooling for antiferromagnetism in optical lattices0 aInteractioninduced adiabatic cooling for antiferromagnetism in o c2007 a064492/1-100 v763 aIn the experimental context of cold-fermion optical lattices, we discuss the possibilities to approach the pseudogap or ordered phases by manipulating the scattering length or the strength of the laser-induced lattice potential. Using the two-particle self-consistent approach, as well as quantum Monte Carlo simulations, we provide isentropic curves for the two- and three-dimensional Hubbard models at half-filling. These quantitative results are important for practical attempts to reach the ordered antiferromagnetic phase in experiments on optical lattices of two-component fermions. We find that adiabatically turning on the interaction in two dimensions to cool the system is not very effective. In three dimensions, adiabatic cooling to the antiferromagnetic phase can be achieved in such a manner, although the cooling efficiency is not as high as initially suggested by dynamical mean-field theory. Adiabatic cooling by turning off the repulsion beginning at strong coupling is possible in certain cases.

1 aDare, A M1 aRaymond, L1 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724301575nas a2200145 4500008004100000245015700041210006900198260000900267300001600276490000700292520103500299100001501334700002401349856005601373 2007 eng d00aNon-perturbative treatment of charge and spin fluctuations in the two-dimensional extended Hubbard model: Extended two-particle self-consistent approach0 aNonperturbative treatment of charge and spin fluctuations in the c2007 a085115/1-120 v763 aWe study the spin and charge fluctuations of the extended Hubbard model with on-site interaction U and first neighbor interaction V on the two-dimensional square lattice in the weak to intermediate coupling regime. We propose an extension of the two-particle self-consistent approximation that includes the effect of functional derivatives of the pair-correlation functions on irreducible spin and charge vertices. These functional derivatives were ignored in our previous work. We evaluate them assuming particle-hole symmetry. The resulting theory satisfies conservation laws and the Mermin-Wagner theorem. Our current results are in much better agreement with benchmark quantum Monte Carlo results. This theory allows us to reliably determine the crossover temperatures toward renormalized-classical regimes, and hence, the dominant instability as a function of U and V. We have considered fillings n=1 and n=0.75. Either spin or charge fluctuations can dominate. The wave vector is self-determined by the approach.

1 aDavoudi, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724601431nas a2200157 4500008004100000245010500041210006900146260000900215300001500224490000700239520091700246100001601163700001401179700002401193856005601217 2007 eng d00aSupersolidity, entropy, and frustration: t-t '-V model of hard-core bosons on the triangular lattice0 aSupersolidity entropy and frustration tt V model of hardcore bos c2007 a144420/1-40 v763 aWe study the properties of t-t(')-V model of hard-core bosons on the triangular lattice that can be realized in optical lattices. By mapping to the spin-1/2 XXZ model in a field, we determine the phase diagram of the t-V model where the supersolid characterized by the ordering pattern (x,x,-2x(')) ("ferrimagnetic" or SS A) is a ground state for chemical potential mu>3V. By turning on either temperature or t(') at half filling (mu=3V), we find a first order transition from SS A to the elusive supersolid characterized by the (x,-x,0) ordering pattern ("antiferromagnetic" or SS C). In addition, we find a large region where a superfluid phase becomes a solid upon increasing temperature at fixed chemical potential. This is an analog of the Pomeranchuk effect driven by the large entropic effects associated with geometric frustration on the triangular lattice.

1 aHassan, S R1 aMedici, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726100483nas a2200145 4500008004100000245009000041210006900131260000900200300001100209490000700220100001500227700001500242700002400257856005600281 2006 eng d00aComment on "Spin correlations in the paramagnetic phase and ring exchange in La2CuO4"0 aComment on Spin correlations in the paramagnetic phase and ring c2006 a0497010 v971 aRaymond, L1 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727601163nas a2200145 4500008004100000245010800041210006900149260000900218300001500227490000700242520067500249100001300924700002400937856005600961 2006 eng d00aMott transition, antiferromagnetism, and d-wave superconductivity in two-dimensional organic conductors0 aMott transition antiferromagnetism and dwave superconductivity i c2006 a046402/1-40 v973 aWe study the Mott transition, antiferromagnetism, and superconductivity in layered organic conductors using the cellular dynamical mean-field theory for the frustrated Hubbard model. A d-wave superconducting phase appears between an antiferromagnetic insulator and a metal for t(')/t=0.3-0.7 or between a nonmagnetic Mott insulator (spin liquid) and a metal for t(')/t >= 0.8, in agreement with experiments on layered organic conductors including kappa-(ET)(2)Cu-2(CN)(3). These phases are separated by a strong first-order transition. The phase diagram gives much insight into the mechanism for d-wave superconductivity. Two predictions are made.

1 aKyung, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727101133nas a2200145 4500008004100000245009700041210006900138260000900207300001600216490000700232520065300239100001500892700002400907856005600931 2006 eng d00aNearest-neighbor repulsion and competing charge and spin order in the extended Hubbard model0 aNearestneighbor repulsion and competing charge and spin order in c2006 a035113/1-150 v743 aWe generalize the two-particle self-consistent approach (TPSC) to study the extended Hubbard model, where nearest-neighbor interaction is present in addition to the usual local screened interaction. Similarities and differences between the TPSC approach and the Singwi, Tosi, Land, Sjolander (STLS) approximation for the electron gas are discussed. The accuracy of our extension of TPSC is assessed by comparisons with Quantum Monte Carlo calculations of Y. Zhang and J. Callaway [Phys. Rev. B 39, 9397 (1989)]. We quantify how a positive off-site interaction enhances staggered charge fluctuations and reduces staggered magnetic order.

1 aDavoudi, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724701404nas a2200157 4500008004100000245015900041210006900200260000900269300001600278490000700294520083700301100001301138700001501151700002401166856005601190 2006 eng d00aPotential-energy-driven (BCS) to kinetic-energy-driven (BEC) pairing in the two-dimensional attractive Hubbard model: Cellular dynamical mean-field theory0 aPotentialenergydriven BCS to kineticenergydriven BEC pairing in c2006 a0245501/1-50 v743 aThe BCS-BEC crossover within the two-dimensional attractive Hubbard model is studied by using the Cellular Dynamical Mean-Field Theory, both in the normal and superconducting ground states. Short-range spatial correlations incorporated in this theory remove the normal-state quasiparticle peak and the first-order transition found in the Dynamical Mean-Field Theory, rendering the normal state crossover smooth. For U smaller than the bandwidth, pairing is driven by the potential energy, while in the opposite case it is driven by the kinetic energy, resembling a recent optical conductivity experiment in cuprates. Phase coherence leads to the appearance of a collective Bogoliubov mode in the density-density correlation function and to the sharpening of the spectral function. (c) 2006 American Institute of Physics.

1 aKyung, B1 aGeorges, A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726401875nas a2200145 4500008004100000245011300041210006900154300001400223490000700237520137300244100002401617700001301641700001901654856005601673 2006 eng d00aPseudogap and high-temperature superconductivity from weak to strong coupling. Towards a quantitative theory0 aPseudogap and hightemperature superconductivity from weak to str a424–4510 v323 aThis is a short review of the theoretical work on the two-dimensional Hubbard model performed in Sherbrooke in the last few years. It is written on the occasion of the twentieth anniversary of the discovery of high-temperature superconductivity. We discuss several approaches, how they were benchmarked and how they agree sufficiently with each other that we can trust that the results are accurate solutions of the Hubbard model. Then comparisons are made with experiment. We show that the Hubbard model does exhibit d-wave superconductivity and antiferromagnetism essentially where they are observed for both hole- and electron-doped cuprates. We also show that the pseudogap phenomenon comes out of these calculations. In the case of electron-doped high temperature superconductors, comparisons with angle-resolved photoemission experiments are nearly quantitative. The value of the pseudogap temperature observed for these compounds in recent photoemission experiments had been predicted by theory before it was observed experimentally. Additional experimental confirmation would be useful. The theoretical methods that are surveyed include mostly the two-particle self-consistent approach, variational cluster perturbation theory (or variational cluster approximation), and cellular dynamical mean-field theory. (c) 2006 American Institute of Physics.

1 aTremblay, A.-M., S.1 aKyung, B1 aSénéchal, D. uhttps://www.physique.usherbrooke.ca/pages/node/728201318nas a2200193 4500008004100000245008100041210006900122260000900191300001600200490000700216520074000223100001300963700001900976700001900995700002401014700001501038700001501053856005601068 2006 eng d00aPseudogap induced by short-range spin correlations in a doped Mott insulator0 aPseudogap induced by shortrange spin correlations in a doped Mot c2006 a1651114/1-60 v733 aWe study the evolution of a Mott-Hubbard insulator into a correlated metal upon doping in the two-dimensional Hubbard model using the cellular dynamical mean-field theory. Short-range spin correlations create two additional bands apart from the familiar Hubbard bands in the spectral function. Even a tiny doping into this insulator causes a jump of the Fermi energy to one of these additional bands and an immediate momentum-dependent suppression of the spectral weight at this Fermi energy. The pseudogap is closely tied to the existence of these bands. This suggests a strong-coupling mechanism that arises from short-range spin correlations and large scattering rates for the pseudogap phenomenon seen in several cuprates.

1 aKyung, B1 aKancharla, S S1 aSénéchal, D.1 aTremblay, A.-M., S.1 aCivelli, M1 aKotliar, G uhttps://www.physique.usherbrooke.ca/pages/node/726602359nas a2200157 4500008004100000245010100041210006900142260000900211300001600220490000700236520185000243100001302093700001502106700002402121856005602145 2006 eng d00aQuantum Monte Carlo study of strongly correlated electrons: Cellular dynamical mean-field theory0 aQuantum Monte Carlo study of strongly correlated electrons Cellu c2006 a205106/1-130 v733 aWe study the Hubbard model using the cellular dynamical mean-field theory (CDMFT) with quantum Monte Carlo (QMC) simulations. We present the algorithmic details of CDMFT with the Hirsch-Fye QMC method for the solution of the self-consistently embedded quantum cluster problem. We use the one- and two-dimensional half filled Hubbard model to gauge the performance of CDMFT+QMC particularly for small clusters by comparing with the exact results and also with other quantum cluster methods. We calculate single-particle Green's functions and self-energies on small clusters to study their size dependence in one and two dimensions. It is shown that in one dimension, CDMFT with two sites in the cluster is already able to describe with high accuracy the evolution of the density as a function of the chemical potential and the compressibility divergence at the Mott transition, in good agreement with the exact Bethe ansatz result. With increasing U the result on small clusters rapidly approaches that of the infinite size cluster. Large scattering rate and a positive slope in the real part of the self-energy in one dimension suggest that the system is a non-Fermi liquid for all the parameters studied here. In two dimensions, at intermediate to strong coupling, even the smallest cluster (N-c=2x2) accounts for more than 95% of the correlation effect of the infinite-size cluster in the single particle spectrum, suggesting that some of the important problems in strongly correlated electron systems may be studied highly accurately with a reasonable computational effort. Finally, as an application that is sensitive to details of correlations, we show that CDMFT+QMC can describe spin-charge separated Luttinger liquid physics in one dimension. The spinon and holon branches appear only for sufficiently large system sizes.

1 aKyung, B1 aKotliar, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726701296nas a2200169 4500008004100000245008200041210006900123300001400192490000700206520077000213100001700983700001301000700001401013700001901027700002401046856005601070 2006 eng d00aStrong- and weak-coupling mechanisms for pseudogap in electron-doped cuprates0 aStrong and weakcoupling mechanisms for pseudogap in electrondope a189–1920 v673 aUsing the two-particle self-consistent approach and cluster perturbation theory for the two-dimensional t-t'-t"-U Hubbard model, we discuss weak- and strong-coupling mechanisms for the pseudogap observed in recent angle resolved photoemission spectroscopy on electron-doped cuprates. In the case of the strong-coupling mechanism, which is more relevant near half-filling, the pseudogap can be mainly driven by short-range correlations near the Mott insulator. In the vicinity of optimal doping, where weak-coupling physics is more relevant, large antiferromagnetic correlation lengths, seen in neutron measurements, are the origin of the pseudogap. The t-J model is not applicable in the latter case. (c) 2006 Elsevier Ltd. All rights reserved.

1 aHankevych, V1 aKyung, B1 aDare, A M1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725800550nas a2200169 4500008004100000245009000041210006900131260000900200300001500209490000700224653001500231100001900246700001800265700001700283700002400300856005600324 2005 eng d00aCompetition between Antiferromagnetism and Superconductivity in High-${T}_c$ Cuprates0 aCompetition between Antiferromagnetism and Superconductivity in c2005 a156404/1-40 v9410aSans titre1 aSénéchal, D.1 aLavertu, P -L1 aMarois, M -A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/530401393nas a2200157 4500008004100000245009300041210006900134260000900203300001600212490000700228520088300235100001801118700001901136700002401155856005601179 2005 eng d00aEffect of superconducting fluctuations on ultrasound in an unconventional superconductor0 aEffect of superconducting fluctuations on ultrasound in an uncon c2005 a024508/1-130 v723 aWe study the renormalization of sound attenuation and sound velocity by fluctuation Cooper pairs in layered superconductors. We consider the influence of s- and d-wave symmetry of the fluctuating order parameter on both longitudinal and transverse phonon modes. We show that both unconventional order parameter symmetry and transverse sound polarization suppress the Aslamazov-Larkin and Maki-Thompson terms, while the density-of-states contribution is the least affected. The combination of these effects can change the sign of the overall fluctuation corrections above T-c. We also compare the results obtained using the Ginzburg-Landau formalism with a microscopic derivation of the fluctuation corrections to the sound velocity in both s- and d-wave superconductors. These calculations are motivated by ongoing ultrasound measurements in organic superconductors.

1 aMar'enko, M S1 aBourbonnais, C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/535801699nas a2200169 4500008004100000245008800041210006900129260000900198300001500207490000700222520115900229100002001388700001901408700002201427700002401449856005601473 2005 eng d00aNeel order, ring exchange, and charge fluctuations in the half-filled Hubbard model0 aNeel order ring exchange and charge fluctuations in the halffill c2005 a115114/1-80 v723 aWe investigate the ground state properties of the two-dimensional half-filled one band Hubbard model in the strong (large-U) to intermediate coupling limit (i.e., away from the strict Heisenberg limit) using an effective spin-only low-energy theory that includes nearest-neighbor exchange, ring exchange, and all other spin interactions to order t(t/U)(3). We show that the operator for the staggered magnetization, transformed for use in the effective theory, differs from that for the order parameter of the spin model by a renormalization factor accounting for the increased charge fluctuations as t/U is increased from the t/U -> 0 Heisenberg limit. These charge fluctuations lead to an increase of the quantum fluctuations over and above those for an S=1/2 antiferromagnet. The renormalization factor ensures that the zero temperature staggered moment for the Hubbard model is a monotonously decreasing function of t/U, despite the fact that the moment of the spin Hamiltonian, which depends on transverse spin fluctuations only, in an increasing function of t/U. We also comment on quantitative aspects of the t/U and 1/S expansions.

1 aDelannoy, J Y P1 aGingras, M J P1 aHoldsworth, P C W1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724901578nas a2200181 4500008004100000245010300041210006900144260000900213300001600222490000700238520100100245100002001246700001701266700001601283700001701299700002401316856005601340 2004 eng d00aHigher order corrections to effective low-energy theories for strongly correlated electron systems0 aHigher order corrections to effective lowenergy theories for str c2004 a235111/1-120 v703 aThree well-known perturbative approaches to deriving low-energy effective theories, the degenerate Brillouin-Wigner perturbation theory (projection method), the canonical transformation, and the resolvent methods, are compared. We use the Hubbard model as an example to show how, to fourth order in hopping t, all methods lead to the same effective theory, namely the t-J model with ring exchange and various correlated hoppings. We emphasize subtle technical difficulties that make such a derivation less trivial to carry out for orders higher than second. We also show that in higher orders, different approaches can lead to seemingly different forms for the low-energy Hamiltonian. All of these forms are equivalent since they are connected by an additional unitary transformation whose generator is given explicitly. The importance of transforming the operators is emphasized and the equivalence of their transformed structure within the different approaches is also demonstrated.

1 aChernyshev, A L1 aGalanakis, D1 aPhillips, P1 aRozhkov, A V1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724001210nas a2200145 4500008004100000245009100041210006900132260000900201300001500210490000700225520073300232100001900965700002400984856005601008 2004 eng d00aHot spots and pseudogaps for hole- and electron-doped high-temperature superconductors0 aHot spots and pseudogaps for hole and electrondoped hightemperat c2004 a126401/1-40 v923 aUsing cluster perturbation theory, it is shown that the spectral weight and pseudogap observed at the Fermi energy in recent angle resolved photoemission spectroscopy of both electron- and hole-doped high-temperature superconductors find their natural explanation within the t-t(')-t('')-U Hubbard model in two dimensions. The value of the interaction U needed to explain the experiments for electron-doped systems at optimal doping is in the weak to intermediate coupling regime where the t-J model is inappropriate. At strong coupling, short-range correlations suffice to create a pseudogap, but at weak-coupling long correlation lengths associated with the antiferromagnetic wave vector are necessary.

1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727901075nas a2200169 4500008004100000245008700041210006900128260000900197300001500206490000700221520055300228100001300781700001700794700001400811700002400825856005600849 2004 eng d00aPseudogap and spin fluctuations in the normal state of the electron-doped cuprates0 aPseudogap and spin fluctuations in the normal state of the elect c2004 a147994/1-40 v933 aWe present reliable many-body calculations for the t-t(')-t('')-U Hubbard model that explain in detail the results of recent angle-resolved photoemission experiments on electron-doped high-temperature superconductors. The origin of the pseudogap is traced to two-dimensional antiferromagnetic spin fluctuations whose calculated temperature-dependent correlation length also agrees with recent neutron scattering measurements. We make specific predictions for photoemission, for neutron scattering, and for the phase diagram.

1 aKyung, B1 aHankevych, V1 aDare, A M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726500587nas a2200169 4500008003900000245008200039210006900121260000900190300001200199490005200211100002100263700001800284700001600302700001900318700002400337856005600361 2004 d00aStrong- and weak-coupling mechanisms for pseudogap in electron-doped cuprates0 aStrong and weakcoupling mechanisms for pseudogap in electrondope c2006 a189-1920 vJournal of Physics and Chemistry of Solids : 671 aHankevych, Vasyl1 aKyung, Bumsoo1 aDaré, A -M1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/756801510nas a2200145 4500008004100000245009700041210006900138300002300207490000700230520101000237100001801247700001901265700002401284856005601308 2004 eng d00aSuperconducting fluctuation corrections to ultrasound attenuation in layered superconductors0 aSuperconducting fluctuation corrections to ultrasound attenuatio a224503-1-224503-120 v693 aWe consider the temperature dependence of the sound attenuation and sound velocity in layered impure metals due to s-wave superconducting fluctuations of the order parameter above the critical temperature. We obtain the dependence on material properties of these fluctuation corrections in the hydrodynamic limit, where the electron mean free path l is much smaller than the wavelength of sound and where the electron collision rate tau(-1) is much larger than the sound frequency. For longitudinal sound propagating perpendicular to the layers, the open Fermi surface condition leads to a suppression of the divergent contributions to leading order, in contrast with the case of paraconductivity. The leading temperature dependent corrections, given by the Aslamazov-Larkin, Maki-Thompson and density-of-states terms, remain finite as T–>T-c. Nevertheless, the sensitivity of new ultrasonic experiments on layered organic conductors should make these fluctuations effects measurable.

1 aMar'enko, M S1 aBourbonnais, C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/542501023nas a2200181 4500008004100000245005800041210005800099260001300157300001400170520048800184100001300672700002400685700001400709700001900723700002400742700001900766856005600785 2004 eng d00aTheoretical Methods For Strongly Correlated Electrons0 aTheoretical Methods For Strongly Correlated Electrons bSpringer a341–3553 aThe conserving approximation scheme to many-body problems was developed by Kadanoff and Baym using the functional-derivative approach. Another approach for the Hubbard model also satisfies conservation laws, but in addition it satisfies the Pauli principle and a number of sum rules. A concise formal derivation of that approach, using functional derivatives, is given in this conference paper to highlight formal analogies and differences with conserving approximations.

1 aAllen, S1 aTremblay, A.-M., S.1 aVilk, Y M1 aSénéchal, D.1 aTremblay, A.-M., S.1 aBourbonnais, C uhttps://www.physique.usherbrooke.ca/pages/node/722601077nas a2200157 4500008004100000245011500041210006900156260000900225300001500234490000700249520055400256100001300810700001600823700002400839856005600863 2003 eng d00aAntiferromagnetic fluctuations and d-wave superconductivity in electron-doped high-temperature superconductors0 aAntiferromagnetic fluctuations and dwave superconductivity in el c2003 a174502/1-50 v683 aWe show that, at weak to intermediate coupling, antiferromagnetic fluctuations enhance d-wave pairing correlations until, as one moves closer to half-filling, the antiferromagnetically induced pseudogap begins to suppress the tendency to superconductivity. The accuracy of our approach is gauged by detailed comparisons with quantum Monte Carlo simulations. The negative pressure dependence of T-c and the existence of photoemission hot spots in electron-doped cuprate superconductors find their natural explanation within this approach.

1 aKyung, B1 aLandry, J S1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726901305nas a2200193 4500008004100000245008500041210006900126300001100195490000700206520072500213653002100938653001400959653001500973100001300988700001601001700001401017700002401031856005601055 2003 eng d00aComment on 'Absence of a Slater Transition in the Two-Dimensional Hubbard Model'0 aComment on Absence of a Slater Transition in the TwoDimensional a0997020 v903 a{In a recent paper, Physical Review Letters 87, 167010/1-4 (2001), Moukouri and Jarrell presented evidence that in the two-dimensional (d=2) Hubbard model at half-filling there is a metal-insulator transition (MIT) at finite temperature even in weak coupling. While we agree with the numerical results of that paper, we arrive at different conclusions: The apparent gap at finite-temperature can be understood, at weak-coupling, as a crossover phenomenon involving large (but not infinite) antiferromagnetic (AFM) correlation length. Phase-space effects on the self-energy in d=2 are crucial, as are the ratio between AFM correlation length and single-particle thermal de Broglie wavelength. In weak coupling

10aCondensed matter10aMany-Body10aSimulation1 aKyung, B1 aLandry, J S1 aPoulin, D1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/622701167nas a2200133 4500008004100000245006900041210006900110300002200179490000700201520073200208100001300940700002400953856005600977 2003 eng d00aEffect of noise on geometric logic gates for quantum computation0 aEffect of noise on geometric logic gates for quantum computation a012308/1-012308/70 v673 aWe introduce the nonadiabatic, or Aharonov-Anandan, geometric phase as a tool for quantum computation and show how this phase on one qubit can be monitored by a second qubit without any dynamical contribution. We also discuss how this geometric phase could be implemented with superconducting charge qubits. While the nonadiabatic geometric phase may circumvent many of the drawbacks related to the adiabatic (Berry) version of geometric gates, we show that the effect of fluctuations of the control parameters on nonadiabatic phase gates is more severe than for the standard dynamic gates. Similarly, fluctuations also affect to a greater extent quantum gates that use the Berry phase instead of the dynamic phase.

1 aBlais, A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/545200459nam a2200145 4500008003900000245005800039210005800097260001900155300000800174490001300182100001900195700002400214700001900238856005600257 2003 d00aTheoretical Methods for Strongly Correlated Electrons0 aTheoretical Methods for Strongly Correlated Electrons aNew Yorkb2003 a3610 vSpringer1 aSénéchal, D.1 aTremblay, A.-M., S.1 aBourbonnais, C uhttps://www.physique.usherbrooke.ca/pages/node/756501713nas a2200157 4500008004100000245011300041210006900154260000900223300001700232490000700249520118900256100001701445700001301462700002401475856005601499 2003 eng d00aWeak ferromagnetism and other instabilities of the two-dimensional t-t(') Hubbard model at van Hove fillings0 aWeak ferromagnetism and other instabilities of the twodimensiona c2003 a2114405/1-110 v683 aWe investigate magnetic and superconducting instabilities of the two-dimensional t-t(') Hubbard model on a square lattice at van Hove densities from weak to intermediate coupling by means of the two-particle self-consistent approach. We find that as the next-nearest-neighbor hopping \t(')\ increases from zero, the leading instability is towards an incommensurate spin-density wave whose wave vector moves slowly away from (pi,pi). For intermediate values of \t(')\, the leading instability is towards d(x)(2)-y(2)-wave superconductivity. For larger \t(')\>0.33t, there are signs of a crossover to ferromagnetism at extremely low temperatures. The suppression of the crossover temperature is driven by Kanamori screening that strongly renormalizes the effective interaction and also causes the crossover temperature to depend only weakly on t('). Electronic self-energy effects for large \t(')\ lead to considerable reduction of the zero-energy single-particle spectral weight beginning at temperatures as high as Tless than or similar to0.1t, an effect that may be detrimental to the existence of a ferromagnetic ground state at weak coupling.

1 aHankevych, V1 aKyung, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725900637nas a2200145 4500008003900000245007300039210006900112260004200181300001000223490013300233100002600366700002400392700001900416856005600435 2003 d00aWhat is the Hamiltonian for parent high-temperature superconductors?0 aWhat is the Hamiltonian for parent hightemperature superconducto bNRC-CNRC Research Press, Ottawac2003 a71-770 vProceedings of the 17th annual international symposium on High Performance Computing Systems and Applications and the OSCAR Symp1 aGagné-Lebrun, Alexis1 aTremblay, A.-M., S.1 aSénéchal, D. uhttps://www.physique.usherbrooke.ca/pages/node/756700409nas a2200097 4500008003900000245011900039210006900158100001300227700002400240856004700264 2002 d00aPhenomenological description of competing antiferromagnetism and d-wave superconductivity in high $T_{c}$ cuprates0 aPhenomenological description of competing antiferromagnetism and1 aKyung, B1 aTremblay, A.-M., S. uhttp://lanl.arxiv.org/abs/cond-mat/020450000590nas a2200181 4500008003900000245007100039210006900110260000900179300001200188490003900200100001300239700002400252700001400276700001900290700002400309700001900333856005600352 2001 d00aConserving approximations vs Two-Particle Self-Consistent Approach0 aConserving approximations vs TwoParticle SelfConsistent Approach b2003 a341-3550 vCRM Series in Mathematical Physics1 aAllen, S1 aTremblay, A.-M., S.1 aVilk, Y M1 aSénéchal, D.1 aTremblay, A.-M., S.1 aBourbonnais, C uhttps://www.physique.usherbrooke.ca/pages/node/756401558nas a2200133 4500008004100000245006100041210006100102300002200163490000700185520113900192100001301331700002401344856005601368 2001 eng d00aNonperturbative approach to the attractive Hubbard model0 aNonperturbative approach to the attractive Hubbard model aart. no.–0751150 v643 aA nonperturbative approach to the single-band attractive Hubbard model is presented in the general context of functional-derivative approaches to many-body theories. As in previous work on the repulsive model, the first step is bused on a local-field-type ansatz, on enforcement of the Pauli principle and a number of crucial sumrules. The Mermin-Wagner theorem in two dimensions is automatically satisfied. At this level, two-particle self-consistency has been achieved. In the second step of the approximation, an improved expression for the self-energy is obtained by using the results of the first step in an exact expression for the self-energy, where the high- and low-frequency behaviors appear separately. The result is a cooperon-like formula. The required vertex corrections are included in this self-energy expression, as required by the absence of a Migdal theorem for this problem. Other approaches to the attractive Hubbard model are critically compared. Physical consequences of the present approach and agreement with Monte Carlo simulations are demonstrated in the accompanying paper (following this one).

1 aAllen, S1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722501102nas a2200145 4500008004100000245007200041210006900113300002200182490000700204520063900211100001300850700001300863700002400876856005600900 2001 eng d00aPairing fluctuations and pseudogaps in the attractive Hubbard model0 aPairing fluctuations and pseudogaps in the attractive Hubbard mo aart. no.–0751160 v643 aThe two-dimensional attractive Hubbard model is studied in the weak-to-intermediate-coupling regime by employing a nonperturbative approach. It is shown that this approach is in quantitative agreement with Monte Carlo calculations for both single-particle and two-particle quantities. Both the density of states and the single-particle spectral weight show a pseudogap at the Fermi energy below some characteristic temperature T*, also in good agreement with quantum Monte Carlo calculations. The pseudogap is caused by critical pairing fluctuations in the low-temperature renormalized classical regime ((h) over bar omega

1 aKyung, B1 aAllen, S1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/726301484nas a2200229 4500008004100000245007900041210006900120300001600189490000700205520082900212653002101041653001401062653001501076100001601091700001301107700001301120700001301133700001401146700001401160700002401174856005601198 2000 eng d00aMany-body theory versus simulations for the pseudogap in the Hubbard model0 aManybody theory versus simulations for the pseudogap in the Hubb a7887–78920 v613 aThe opening of a critical-fluctuation-induced pseudogap (or precursor pseudogap) in the one-particle spectral weight of the half-filled two-dimensional Hubbard model is discussed. This pseudogap, appearing in our Monte Carlo simulations, may be obtained from many-body techniques that use Green functions and vertex corrections that are at the same level of approximation. Self-consistent theories of the Eliashberg type (such as the fluctuation exchange approximation) use renormalized Green functions and bare vertices in a context where there is no Migdal theorem. They do not find the pseudogap, in quantitative and qualitative disagreement with simulations, suggesting these methods are inadequate for this problem. Differences between precursor pseudogaps and strong-coupling pseudogaps are also discussed.

10aCondensed matter10aMany-Body10aSimulation1 aMoukouri, S1 aAllen, S1 aLemay, F1 aKyung, B1 aPoulin, D1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/622400511nas a2200145 4500008004100000245009900041210006900140260001500209300000800224653001500232100002400247700001900271700001900290856005600309 2000 eng d00aStrong correlations in low dimensional conductors: What are they and where are the challenges?0 aStrong correlations in low dimensional conductors What are they cSept./Oct. a22910aSans titre1 aTremblay, A.-M., S.1 aBourbonnais, C1 aSénéchal, D. uhttps://www.physique.usherbrooke.ca/pages/node/529301272nas a2200157 4500008004100000245006100041210006000102300001300162490000700175520080200182653001500984100001600999700001901015700002401034856005601058 2000 eng d00aStrong-coupling perturbation theory of the Hubbard model0 aStrongcoupling perturbation theory of the Hubbard model a85–1050 v163 aThe strong-coupling perturbation theory of the Hubbard model is presented and carried out tu order (t/U)(5) for the one-particle Green function In arbitrary dimension. The spectral weight A(k,omega) is expressed as a Jacobi continued fraction and compared with new Monte-Carlo data of the one-dimensional, half-filled Hubbard model. Different regimes (insulator, conductor and short-range antiferromagnet) are identified in the temperature-hopping integral (T, t) plane. This work completes a first paper on the subject (Phys. Rev. Lett. 80, 5389 (1998)) by providing details on diagrammatic rules and higher-order results. In addition, the non half-filled case, infinite resummations of diagrams and the double occupancy are discussed. Various tests: of the method are also presented.

10aSans titre1 aPairault, S1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/533800572nas a2200145 4500008003900000020001800039022001500057245006000072210005900132260006800191300001200259490007500271100002400346856005600370 1999 d a9782894431269 a289443126000aMathématiques, physique et technologies au XXe siècle0 aMathématiques physique et technologies au XXe siècle aSherbrookebLes éditions du griffon d'argile, Sainte-Foyc2000 a179-1930 vActes du 42e congrès annuel de l'Association mathématique du Québec1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/756301231nas a2200169 4500008004100000245005800041210005800099300001600157490000700173520074100180100001300921700001700934700001600951700001400967700002400981856005601005 1999 eng d00aRole of symmetry and dimension in pseudogap phenomena0 aRole of symmetry and dimension in pseudogap phenomena a4128–41310 v833 aThe attractive Hubbard model in d = 2 Ts studied through Monte Carlo simulations at intermediate coupling. There is a crossover temperature T-X where a pseudogap appears with concomitant precursors of Bogoliubov quasiparticles that are not local pairs. The pseudogap in A(k(F), omega) occurs in the renormalized classical regime when the correlation length is larger than the direction-dependent thermal de Broglie wavelength, xi(th) = (h) over bar nu(F)(k)/k(B)T. The ratio T-X/T-c for the pseudogap may be made arbitrarily large when the system is close to a point where the order parameter has SO(n) symmetry with n > 2. This is relevant in the context of SO(5) theories of high T-c but has more general applicability.

1 aAllen, S1 aTouchette, H1 aMoukouri, S1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722401580nas a2200169 4500008004100000245010400041210006900145300001400214490000700228520103000235100001501265700001901280700001701299700001401316700002401330856005601354 1999 eng d00aSpin susceptibility of interacting electrons in one dimension: Luttinger liquid and lattice effects0 aSpin susceptibility of interacting electrons in one dimension Lu a351–3650 v123 aThe temperature-dependent uniform magnetic susceptibility of interacting electrons in one dimension is calculated using several methods. At low temperature, the renormalization group reveals that the Luttinger liquid spin susceptibility chi (T) approaches zero temperature with an infinite slope in striking contrast with the Fermi liquid result and with the behavior of the compressibility in the absence of umklapp scattering. This effect comes from the leading marginally irrelevant operator, in analogy with the Heisenberg spin 1/2 antiferromagnetic chain. Comparisons with Monte Carlo simulations at higher temperature reveal that non-logarithmic terms are important in that regime. These contributions are evaluated from an effective interaction that includes the same set of diagrams as those that give the leading logarithmic terms in the renormalization group approach. Comments on the third law of thermodynamics as well as reasons for the failure of approaches that work in higher dimensions are given.

1 aNelisse, H1 aBourbonnais, C1 aTouchette, H1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/542101277nas a2200181 4500008004100000245011800041210006900159300001600228490000700244520069200251100001400943700001300957700001700970700001600987700001201003700002401015856005601039 1998 eng d00aAttractive Hubbard model and single-particle pseudogap caused by classical pairing fluctuations in two-dimensions0 aAttractive Hubbard model and singleparticle pseudogap caused by a1873–18750 v593 aIt is shown that in the two-dimensional attractive Hubbard model, the mean-field phase transition is replaced by a renormalized classical regime of fluctuations where a pseudogap opens up in the single-particle spectral weight. It is argued that this pseudogap and precursors of the ordered state quasiparticles can occur only in strongly anisotropic quasi-two-dimensional materials. This precursor phenomenon differs from preformed local pairs. Further, while critical antiferromagnetic fluctuations would also lead to a pseudogap in the repulsive model, there are some important differences with thr superconducting case. (C) 1998 Elsevier Science Ltd. All rights reserved.

1 aVilk, Y M1 aAllen, S1 aTouchette, H1 aMoukouri, S1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728801034nas a2200145 4500008004100000245005200041210005100093300001600144490000700160520060600167100001600773700001900789700002400808856005600832 1998 eng d00aStrong-coupling expansion for the Hubbard model0 aStrongcoupling expansion for the Hubbard model a5389–53920 v803 aA strong-coupling expansion for models of correlated electrons in any dimension is presented. The method is applied to the Hubbard model in d dimensions and compared with numerical results in d = 1. Third order expansion of the Green's function suffices to exhibit both the Mott metal-insulator transition and a low-temperature regime where antiferromagnetic correlations are strong. It is predicted that some of the weak photoemission signals observed in one-dimensional systems such as SrCuO2 should become stronger as temperature increases away from the spin-charge separated state.

1 aPairault, S1 aSénéchal, D.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/727503221nas a2200133 4500008004100000245009100041210006900132300001600201490000600217520277000223100001402993700002403007856005603031 1997 eng d00aNon-perturbative many-body approach to the Hubbard model and single-particle pseudogap0 aNonperturbative manybody approach to the Hubbard model and singl a1309–13680 v73 aA new approach to the single-band Hubbard model is described in the general context of many-body theories. It is based on enforcing conservation laws, the Pauli principle and a number of crucial sum-rules. More specifically, spin and charge susceptibilities are expressed, in a conserving approximation, as a function of two irreducible vertices whose values are found by imposing the local Pauli principle [n(up arrow)(2)] = [n(up arrow)] as well as the local-moment sum-rule ana consistency with the equations of motion in a local-field approximation. The Mermin-Wagner theorem in two dimensions is automatically satisfied. The effect of collective modes on single-particle properties is then obtained by a paramagnon-like formula that is consistent with the two-particle properties in the sense that the potential energy obtained from Tr Sigma G is identical to that obtained using the fluctuation-dissipation theorem for susceptibilities. Since there is no Migdal theorem controlling the effect of spin and charge fluctuations on the self-energy, the required vertex corrections are included. It is shown that the theory is in quantitative agreement with Monte Carlo simulations for both single-particle and two-particle properties. The theory predicts a magnetic phase diagram where magnetic order persists away from half-filling but where ferromagnetism is completely suppressed. Both quantum-critical and renormalized-classical behavior can occur in certain parameter ranges. It is shown that in the renormalized classical regime, spin fluctuations lead to precursors of antiferromagnetic bands (shadow bands) and to the destruction of the Fermi-liquid quasiparticles in a wide temperature range above the zero-temperature phase transition. The upper critical dimension for this phenomenon is three. The analogous phenomenon of pairing pseudogap can occur in the attractive model in two dimensions when the pairing fluctuations become critical. Simple analytical expressions for the self-energy are derived in both the magnetic and pairing pseudogap regimes. Other approaches, such as paramagnon, self-consistent fluctuation exchange approximation (FLEX), and pseudo-potential parquet approaches are critically compared. In particular, it is argued that the failure of the FLEX approximation to reproduce the pseudogap and the precursors AFM bands in the weak coupling regime and the Hubbard bands in the strong coupling regime is due to inconsistent treatment of vertex corrections in the expression for the self-energy. Treating the spin fluctuations as if there was a Migdal's theorem can lead not only to quantitatively wrong results but also to qualitatively wrong predictions, in particular with regard to the single-particle pseudogap.

1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/729101457nas a2200145 4500008004100000245011200041210006900153300001800222490000700240520095600247100001401203700001401217700002401231856005601255 1996 eng d00aCrossover from two- to three-dimensional critical behavior for nearly antiferromagnetic itinerant electrons0 aCrossover from two to threedimensional critical behavior for nea a14236–142510 v533 aThe crossover from two- to three-dimensional critical behavior of nearly antiferromagnetic itinerant electrons is studied in a regime where the interplane single-particle motion of electrons is quantum mechanically incoherent because of thermal fluctuations. This is a relevant regime for very anisotropic materials like the cuprates. The problem is studied within the two-particle self-consistent (TPSC) approach, which has been previously shown to give a quantitative description of Monte Carlo data for the Hubbard model. It is shown that the TPSC approach belongs to the n–>infinity limit of the O(n) universality class. However, contrary to the usual approaches, cutoffs appear naturally in the microscopic TPSC theory so that parameter-free calculations can be done for Hubbard models with. arbitrary band structure. A general discussion of universality in the renormalized-classical crossover from d=2 to d=3 is also given.

1 aDare, A M1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724401062nas a2200133 4500008004100000245009000041210006900131300001400200490000700214520061300221100001400834700002400848856005600872 1996 eng d00aDestruction of Fermi-liquid quasiparticles in two dimensions by critical fluctuations0 aDestruction of Fermiliquid quasiparticles in two dimensions by c a159–1640 v333 aIt is shown that an analytic approach which includes vertex corrections in a paramagnon-like self-energy can quantitatively explain the two-dimensional Hubbard model in the weak-to-intermediate coupling regime. All parameters are determined self-consistently. This approach clearly shows that in two dimensions Fermi-liquid quasiparticles disappear in the finite-temperature paramagnetic state when the antiferromagnetic correlation length becomes larger than the electronic thermal de Broglie wavelength. Quantum Monte Carlo results are used to compare the accuracy of this approach with others.

1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/729200614nas a2200205 4500008003900000020001500039022001800054245004100072210004100113260001800154300001000172490005200182100001800234700001900252700002400271700001400295700001800309700002500327856005600352 1996 d a2863322044 a978286332204800aLuttinger liquids coupled by hopping0 aLuttinger liquids coupled by hopping aMoriondc1996 a65-790 vProceedings of the XXXIst Rencontres de Moriond1 aBoies, Daniel1 aBourbonnais, C1 aTremblay, A.-M., S.1 aMartin, T1 aMontambaux, G1 aVân, Trân Thanh, J uhttps://www.physique.usherbrooke.ca/pages/node/756200440nas a2200133 4500008003900000245007100039210006900110260001200179300001400191490000700205100001400212700002400226856005600250 1995 d00aDestruction of Fermi liquid by spin fluctuations in two dimensions0 aDestruction of Fermi liquid by spin fluctuations in two dimensio c12/1995 a1769-17710 v561 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/756100431nas a2200121 4500008004100000245008000041210006900121300001600190490000700206100001600213700002400229856005600253 1995 eng d00aField-theory and 2nd Renormalization-group For Multifractals In Percolation0 aFieldtheory and 2nd Renormalizationgroup For Multifractals In Pe a4095–41040 v511 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725201737nas a2200169 4500008004100000245009100041210006900132300001800201490000700219520120100226100001801427700001401445700001401459700001401473700002401487856005601511 1995 eng d00aMagnetic and pair correlations of the Hubbard model with next-nearest-neighbor hopping0 aMagnetic and pair correlations of the Hubbard model with nextnea a16255–162630 v523 aA combination of analytical approaches and quantum Monte Carlo simulations is used to study both magnetic and pairing correlations for a version of the Hubbard model that includes second-neighbor hopping t'=-0.35t as a model for high-temperature superconductors. Magnetic properties are analyzed using the two-particle self-consistent approach. The maximum in magnetic susceptibility as a function of doping appears both at finite t' and at t'=0 but for two totally different physical reasons. When t'=0, it is induced by antiferromagnetic correlations while at t'=-0.35t it is a band structure effect amplified by interactions. Finally, pairing fluctuations are compared with T-matrix results to disentangle the effects of van Hove singularity and of nesting on superconducting correlations. The addition of antiferromagnetic fluctuations increases slightly the d-wave superconducting correlations despite the presence of a van Hove singularity which tends to decrease them in the repulsive model. Some aspects of the phase diagram and some subtleties of finite-size scaling in Monte Carlo simulations, such as inverted finite-size dependence, are also discussed.

1 aVeilleux, A F1 aDare, A M1 aChen, L A1 aVilk, Y M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728702292nas a2200145 4500008004100000245008100041210006900122300001600191490000600207520182300213100001302036700001702049700002402066856005602090 1995 eng d00aNagaoka Ferromagnetism As A Test of Slave-fermion and Slave-boson Approaches0 aNagaoka Ferromagnetism As A Test of Slavefermion and Slaveboson a1001–10240 v93 aThe ferromagnetic to paramagnetic transition in the Nagaoka (U = infinity) limit of the Hubbard Hamiltonian is used to test the applicability of slave-boson and slave-fermion (Schwinger boson) functional-integral approaches. Within the slave-fermion formalism to one-loop order, the ferromagnetic phase is stable to spin-wave, gauge field, and longitudinal fluctuations over a doping interval that is much too large compared with other approaches. Furthermore, nonbipartite lattices such as hcp or fee lattices are ferromagnetic for t > 0 over a wider doping interval than for t < 0, in qualitative disagreement with all other types of calculations. It is possible to remedy all these defects in order to reach agreement, at least qualitatively, with previous studies. It suffices to take the point of view that in the U = infinity limit it is best to represent the paramagnetic phase as the mean-field solution of the slave-boson representation, and the ferromagnetic phase as the mean-field solution of the slave-fermion representation. The transition between both phases is taken to occur at the critical hole doping where the ground state energies are equal. This seems to give the best possible comparison with other approaches, despite the lack of a variational principle justifying comparisons of energies between slave-fermion and slave-boson representations. On bipartite lattices, the critical hole density found analytically by this procedure, delta(c) = 1/3, is identical to the critical density obtained in the Kotliar-Ruckenstein slave-boson approach. This value of delta(c) is also close to various other estimates. Nevertheless, non-bipartite lattices with t > 0 remain ferromagnetic over a small but finite doping interval, in quantitative disagreement with some other approaches.

1 aBoies, D1 aJACKSON, F A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723100450nas a2200133 4500008004100000245007500041210006900116300001200185490000700197100001300204700001900217700002400236856005600260 1995 eng d00aOne-particle and two-particle instability of coupled luttinger liquids0 aOneparticle and twoparticle instability of coupled luttinger liq a968-9710 v741 aBoies, D1 aBourbonnais, C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/540601041nas a2200145 4500008004100000245004600041210004600087260001200133300001200145490000700157520064700164100001800811700002400829856004200853 1995 eng d00aSpiral Magnets As Gapless Mott Insulators0 aSpiral Magnets As Gapless Mott Insulators c01/1995 a37–420 v293 aIn the large-U limit, the ground state of the half-filled, nearest-neighbor Hubbard model on the triangular lattice is the three-sublattice antiferromagnet. In sharp contrast with the square-lattice case, where Goldstone modes never have a charge component, it is shown that beyond leading order in t/U the three Goldstone modes on the triangular lattice, at finite q, are a linear combination of spin and charge. This leads to non-vanishing conductivity at any finite frequency, even though the magnet remains insulating at zero frequency. More generally, non-collinear spin order should lead to such gapless insulating behavior.

1 aCôté, René1 aTremblay, A.-M., S. uhttp://stacks.iop.org/0295-5075/29/3701168nas a2200145 4500008004100000245009200041210006900133300001600202490000800218520067600226100001400902700001200916700002400928856007000952 1994 eng d00a2-particle Self-consistent Theory For Spin and Charge Fluctuations In the Hubbard-model0 a2particle Selfconsistent Theory For Spin and Charge Fluctuations a2235–22360 v2353 aA theory which is self-consistent at the two-particle level is presented for both spin and charge fluctuations in the Hubbard model. It is in quantitative agreement with Monte Carlo data at least up to intermediate coupling (U similar to 8t) It includes both short-wavelength quantum renormalization effects, and long-wavelength thermal fluctuations which can destroy long-range order in two dimensions. This last effect leads to a small energy scale, as often observed in high temperature superconductors. The theory is conserving, satisfies the Pauli principle and includes three-particle correlations necessary to account for the incipient Mott transition.

1 aVilk, Y M1 aChen, L1 aTremblay, A.-M., S. uhttp://www.sciencedirect.com/science/article/pii/092145349492339601808nas a2200145 4500008004100000245012700041210006900168300001600237490000700253520129500260100001501555700001201570700002401582856005601606 1994 eng d00aComparisons Between Monte-carlo Simulations and A Simple Crossing-symmetrical Approach To the Hubbard-model At Low-density0 aComparisons Between Montecarlo Simulations and A Simple Crossing a4106–41180 v493 aA simple crossing-symmetric approximation for the fully reducible vertex is compared with Monte Carlo simulations of the two-dimensional Hubbard model. Up to quarter-filling, in the intermediate coupling regime, accuracies better than 10% are obtained for several static correlation functions, including spin and charge, as well as the pairing channels most widely studied in the context of high-T(c) superconductivity. The accuracy is generally better for the pairing channels. The results shed light on the applicability of the renormalized generalized-random-phase-approximation scheme, its relation to Fermi-liquid theory, and on the regime where nontrivial effects may appear in pairing channels. The approximation under study consists in assuming that for parallel spins the fully reducible particle-particle vertex vanishes, while for antiparallel spins it is equal to the T matrix. The fully reducible particle-hole vertex is then obtained from the latter vertex by using crossing symmetry. This simple approximation is not conserving but it preserves global symmetries. It suggests that Monte Carlo results for the two-dimensional Hubbard model in small systems at low density and intermediate coupling can be interpreted using a weakly correlated Fermi-liquid picture.

1 aDaré, A M1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724201028nas a2200145 4500008004100000245014500041210006900186300001600255490000800271520049600279100001500775700001200790700002400802856005600826 1994 eng d00aCorrelation-functions of the Hubbard-model At Low-density In A Crossing-symmetrical Approximation - Comparisons With Monte-carlo Simulations0 aCorrelationfunctions of the Hubbardmodel At Lowdensity In A Cros a1413–14140 v1943 aThe accuracy of a simple crossing-symmetric approximation for the fully reducible vertex is tested by comparisons of the spin, charge, and pairing correlations with those obtained by Monte Carlo simulations of the two-dimensional Hubbard model. The approximation under study consists in assuming that for parallel spins the fully reducible vertex vanishes, while for anti-parallel spins it is equal to the T-matrix. Up to quarter-filling, accuracies better than 10% are obtained.

1 aDaré, A M1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/724101312nas a2200133 4500008004100000245007500041210006900116300001600185490000700201520087600208100001401084700002401098856005601122 1994 eng d00aMagnetic-susceptibility of the two-dimensional Hubbard-model - Comment0 aMagneticsusceptibility of the twodimensional Hubbardmodel Commen a4338–43400 v493 aThe observed magnetic spin susceptibility of high-temperature superconductors such as La2-xSrxCuO4 increases when x increases from zero, i.e., as one dopes away from half-filling. Recent Monte Carlo simulations of A. Moreo [Phys. Rev. B 48, 3380 (1993)] suggest that this behavior can be reproduced by the two-dimensional Hubbard model only at large coupling, namely, U/t of order 10. Using longer runs, our Monte Carlo simulations show that the same behavior as for U/t = 10 is obtained even in the intermediate coupling regime (U/t = 4), as long as the temperature is low enough (T = t/6) that strong antiferromagnetic correlations are building up at half-filling. These results are consistent with the fact that in two dimensions, the generalized random phase approximation should fail in the pa-rameter range where it predicts a magnetic phase transition.

1 aChen, L A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723500627nas a2200181 4500008003900000245012700039210007000166260000900236300001000245490003200255100001800287700001600305700001200321700001400333700002400347700001800371856005600389 1994 d00aQuantum Monte Carlo simulations for a model of high-tem¬perature superconductors: effect of next-nearest-neighbor hopping0 aQuantum Monte Carlo simulations for a model of hightem¬perature c1994 a78-850 vUniversity of Toronto Press1 aVeilleux, A F1 aDaré, A -M1 aChen, L1 aVilk, Y M1 aTremblay, A.-M., S.1 aRoss, John, W uhttps://www.physique.usherbrooke.ca/pages/node/756001091nas a2200145 4500008004100000245006400041210006300105300001800168490000700186520064600193100001400839700001200853700002400865856005600889 1994 eng d00aTheory of Spin and Charge Fluctuations In the Hubbard-model0 aTheory of Spin and Charge Fluctuations In the Hubbardmodel a13267–132700 v493 aA self-consistent theory of both spin and charge fluctuations in the Hubbard model is presented. It is in quantitative agreement with Monte Carlo data at least up to intermediate coupling (U approximately 8t). It includes both short-wavelength quantum renormalization effects, and long-wavelength thermal fluctuations, which can destroy long-range order in two dimensions. This last effect leads to a small energy scale, as often observed in high-temperature superconductors. The theory is conserving, satisfies the Pauli principle, and includes three-particle correlations necessary to account for the incipient Mott transition.

1 aVilk, Y M1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728900867nas a2200145 4500008004100000245010600041210006900147300001800216490000700234520037500241100001200616700001300628700002400641856005600665 1993 eng d00aFlux-quantization In Rings For Hubbard (attractive and Repulsive) and T-j-like Hamiltonians - Comment0 aFluxquantization In Rings For Hubbard attractive and Repulsive a a15316–153180 v473 aIt is shown for three models with strong correlations that the value of the total spin of the ground state of finite-size rings with two fermions (holes or electrons) can change as a function of magnetic flux PHI. It is concluded that the magnetic flux periodicity may be used as a test of binding only if one also checks for changes in spin quantum numbers.

1 aChen, L1 aMei, C J1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723801601nas a2200145 4500008004100000245009600041210006900137300001800206490000700224520111700231100001501348700001201363700002401375856005601399 1993 eng d00aMagnetic Neutron-scattering From 2-dimensional Lattice Electrons - the Case of La2-xsrxcuo40 aMagnetic Neutronscattering From 2dimensional Lattice Electrons t a15217–152410 v473 aIt is found that the one-band Hubbard model, in the weak- to intermediate-coupling regime, can account qualitatively for magnetic-neutron-scattering experiments in the paramagnetic phase of La2-xSrxCuO4 when second-neighbor hopping is included. However, the peak positions, which in two dimensions are determined mostly by the band structure, cannot agree quantitatively with the experimental results when concentration-independent band parameters are used. More importantly, while the energy scale of roughly 150 K seen in the experiments can come from second-neighbor hopping, it arises most naturally if one is very close to a magnetic instability. The proximity to a magnetic instability can be checked experimentally by measuring the relative size of the lattice equivalent of 2k(F) anomalies that appear closer to the origin in wave-vector space. Such lattice-2k(F) anomalies would allow magnetic neutron scattering to become a spectroscopic tool for the two-dimensional Fermi surface. Finally, exact results are also given for the imaginary part of the Lindhard function on the square lattice.

1 aBénard, P1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722901003nas a2200145 4500008004100000245009600041210006900137300001400206490000700220520052300227100001500750700001200765700002400777856005600801 1993 eng d00aNeutron-scattering Measurements As A Test of Theories of High-temperature Superconductivity0 aNeutronscattering Measurements As A Test of Theories of Hightemp a589–5920 v473 aIt is shown that the Hubbard model in the intermediate-coupling regime can qualitatively explain neutron-scattering experiments in La2-xSrxCuO4 only if there are strong magnetic fluctuations in the system. By contrast, the marginal-Fermi-liquid approach explains the data without appealing at all to strong magnetic fluctuations. It is shown that the strength of the magnetic fluctuations can be estimated by detecting incommensurate peaks located near the zone center using neutron-scattering experiments.

1 aBénard, P1 aChen, L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722801146nas a2200145 4500008004100000245007500041210006900116300001400185490000600199520067600205100001500881700002400896700002400920856005600944 1993 eng d00aScaling Behavior of Multifractal-moment Distributions Near Criticality0 aScaling Behavior of Multifractalmoment Distributions Near Critic a323–3300 v33 aSample to sample fluctuations of the multifractal moments of percolating random-resistor networks are studied via Monte Carlo simulations. For systems of size L, these fluctuations depend on DELTAp, the deviation from the critical concentration, only through the scaled variable DELTApL1/nu. At DELTAp = 0, these fluctuations depend on h, the ratio of the good and bad conductances, only through hL(phi). This is consistent with a previously proposed scaling ansatz for the joint probability distribution of multifractal moments. In the DELTAp not-equal 0 direction, the relative fluctuations are largest when the bulk correlation length is of the order of L.

1 aAlbinet, G1 aTremblay, A.-M., S.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722300948nas a2200133 4500008004100000245005000041210005000091300001600141490000700157520055600164100001400720700002400734856005600758 1993 eng d00aSymmetry and Nodes of the Superconducting Gap0 aSymmetry and Nodes of the Superconducting Gap a1381–13840 v543 aFor pairing potentials which act only in the vicinity of the Fermi-surface, a Fermi-surface harmonics expansion of the gap function is appropriate. After a general symmetry discussion, it is pointed-out that the first extended s-wave occuring in the Fermi-surface harmonics expansion of the gap function a) is closely related to the usual d-waves b) it can have a large number of nodes. This may reconcile the experiments which see nodes in the gap and neutron-scattering experiments which cannot resolve the anistropy in the gap function.

1 aChen, L A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723601513nas a2200133 4500008004100000245009100041210006900132300001400201490000600215520105200221100001201273700002401285856007001309 1992 eng d00aDeterminant Monte-carlo For the Hubbard-model With Arbitrarily Gauged Auxiliary Fields0 aDeterminant Montecarlo For the Hubbardmodel With Arbitrarily Gau a547–5600 v63 aMonte Carlo methods for the Hubbard model rely on a Hubbard-Stratonovich (HS) decomposition (auxiliary field method) to perform importance sampling on classical variables. Freedom in the choice of the local HS fields can be formally seen as a gauge choice. While the choice of gauge does not influence observable quantities, it may influence intermediate quantities in the calculation, such as the famous "fermion sign", and it may also influence the efficiency with which the algorithm explores phase space. The effect of arbitrary gauge choices on both aspects of the algorithm are investigated. It is found that in the single spin-flip determinantal approach, certain gauges lead to a better exploration of phase space. This improvement is demonstrated, in the intermediate coupling regime, by histograms which for the first time show the behavior expected from grand canonical simulations. It is also found that the improved phase space exploration can in practice offset the apparent disadvantage of a smaller fermion sign.

1 aChen, L1 aTremblay, A.-M., S. uhttps://www.worldscientific.com/doi/abs/10.1142/S021797929200032301105nas a2200157 4500008004100000245005100041210005100092300001400143490000800157520064700165100002400812700002400836700001500860700001600875856005600891 1992 eng d00aHow Many Correlation Lengths For Multifractals0 aHow Many Correlation Lengths For Multifractals a398–4100 v1833 aIt is shown, here in the context of percolation, that one can have multifractal behavior and at the same time a single correlation length. This length sets the scale below which non-trivial scaling behavior occurs and it is controlled by a few relevant operators. as in ordinary critical phenomena. All other correlation lengths may be obtained from simple metric factors. The quantities which lead to an infinite set of exponents are described by a second renormalization group which is slaked to the first one which determines the correlation length. The results are relevant also to the problem of noise in percolating systems.

1 aTremblay, A.-M., S.1 aTremblay, A.-M., S.1 aAlbinet, G1 aFourcade, B uhttps://www.physique.usherbrooke.ca/pages/node/728401810nas a2200145 4500008004100000245010300041210006900144300001400213490000700227520131100234100002401545700001501569700002401584856005601608 1992 eng d00aNoise and Crossover Exponent In Conductor-insulator Mixtures and Superconductor-conductor Mixtures0 aNoise and Crossover Exponent In Conductorinsulator Mixtures and a755–7670 v453 aThe resistance noise of random conductor-insulator mixtures is studied in the case where the insulators have a small but finite conductance. The conductance noise of superconductor-conductor mixtures is similarly studied when the superconductors have a small but finite resistance. The Migdal-Kadanoff renormalization-group calculations that lead to the appropriate linear and nonlinear scaling fields for these problems are discussed in detail. The corresponding homogeneity relations for the total noise are valid near the unstable percolation fixed point whatever the relative size of the microscopic noises. The exponents of the superconductor-conductor mixture appear naturally in the scaling form of the noise coming from the imperfect insulators. Analogously, the exponents of the conductor-insulator mixture enter in the scaling form of the noise coming from the imperfect superconductors in the superconductor-conductor problem. Monte Carlo simulations in two and three dimensions confirm that the scaling predictions are valid well beyond the domain of applicability of the Migdal-Kadanoff approach. For all multifractal moments and both types of mixtures, there is a single crossover exponent and a single correlation length associated with the ratio of the microscopic conductances.

1 aTremblay, A.-M., S.1 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728501043nas a2200169 4500008004100000245007600041210006900117300001600186490000700202520051300209100001700722700001400739700001600753700002400769700002400793856005600817 1992 eng d00aOne-dimensional vibrations and disorder - the Zr1-xhfxs3 solid-solution0 aOnedimensional vibrations and disorder the Zr1xhfxs3 solidsoluti a5183–51930 v463 aIn the trichalcogenide family of compounds Zr1-xHfxS3 there is a frequency range where the optic modes are expected to be describable by a simple one-dimensional model. It is shown that the disorder-induced linewidth in the relevant frequency range could be consistent with theoretical calculations for a simple diatomic chain model. The vibrations involved are along the chain direction and are of B(g) type. All the B(g) modes of this family of compounds are also here unequivocally identified.

1 aAit-Ouali, A1 aJandl, S.1 aMarinier, P1 aLopez-Castillo, J M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722200572nas a2200145 4500008003900000245015000039210006900189260002800258100001200286700001900298700001200317700002400329700001700353856005600370 1991 d00aThe influence of spin fluctuations on the temperature dependance of the magnetic susceptibility and nuclear relaxation in high Tc superconductors0 ainfluence of spin fluctuations on the temperature dependance of aZurich, Suissec08/19911 aLi, T W1 aBourbonnais, C1 aChen, L1 aTremblay, A.-M., S.1 aBrinkmann, D uhttps://www.physique.usherbrooke.ca/pages/node/757901053nas a2200157 4500008004100000245005900041210005600100300001400156490000700170520059700177100001200774700001900786700001000805700002400815856005600839 1991 eng d00aMagnetic-properties of the 2-dimensional Hubbard-model0 aMagneticproperties of the 2dimensional Hubbardmodel a369–3720 v663 aMonte Carlo simulations of the magnetic structure factor of the two-dimensional Hubbard model are in qualitative agreement with the slave-boson approach and, in the low-temperature intermediate-coupling limit, they are in even better quantitative agreement with the random-phase approximation, as long as a renormalized repulsion U is used. This renormalization comes from maximally crossed diagrams, which account for two-body short-range correlations. One of the consequences is that Stoner ferromagnetism is not a generic property of the two-dimensional one-band Hubbard model.

1 aChen, L1 aBourbonnais, C1 aLi, T1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/723701111nas a2200145 4500008004100000245007800041210006900119300001800188490000700206520063300213100002400846700001500870700002400885856005600909 1991 eng d00aNoise and crossover exponent In the two-component random resistor network0 aNoise and crossover exponent In the twocomponent random resistor a11546–115490 v433 aThe resistance noise of random conductor-insulator mixtures is studied in the case where the insulator has a small, but finite conductivity. Based on the structure of a simple renormalization group, a general homogeneity relation for the noise of both insulators and conductors is suggested. The expression for the total noise is valid from the noisy-conductor quiet-insulator limit to the quiet-conductor noisy-insulator limit. Monte Carlo simulations confirm the scaling predictions. For all multifractal moments, there is a single crossover exponent associated with the small finite conductivity of the insulator.

1 aTremblay, A.-M., S.1 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/728601550nas a2200133 4500008004100000245011400041210006900155300001400224490000700238520107200245100001901317700002401336856005601360 1991 eng d00aRandom Mixtures With Orientational Order, and the Anisotropic Resistivity Tensor of High-t(c) Superconductors0 aRandom Mixtures With Orientational Order and the Anisotropic Res a379–3830 v693 aBy generalizing effective-medium theory to the case of orientationally ordered but positionally disordered two-component mixtures, it is shown that the anisotropic dielectric tensor of oxide superconductors can be extracted from microwave measurements on oriented crystallites of YBa2Cu3O7-x embedded in epoxy. Surprisingly, this technique appears to be the only one which can access the resistivity perpendicular to the copper-oxide planes in crystallites that are too small for depositing electrodes. This possibility arises in part because the real part of the dielectric constant of oxide superconductors has a large magnitude . The validity of the effective-medium approach for orientationally ordered mixtures is corroborated by simulations on two-dimensional anisotropic random resistor networks. Analysis of the experimental data suggests that the zero-temperature limit of the finite-frequency resistivity does not vanish along the c axis, a result which would imply the existence of states at the Fermi surface even in the superconducting state.

1 aDiazguilera, A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725000455nas a2200121 4500008004100000245010400041210006900145300001600214490000700230100001600237700002400253856005600277 1990 eng d00aAmplitudes of Multifractal Moments At the Onset of Chaos - Universal Ratios and Crossover Functions0 aAmplitudes of Multifractal Moments At the Onset of Chaos Univers a2659–26620 v641 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725600432nas a2200121 4500008004100000245008100041210006900122300001600191490000700207100001600214700002400230856005600254 1990 eng d00aBreakdown of Multifractal Behavior In Diffusion-limited Aggregates - Comment0 aBreakdown of Multifractal Behavior In Diffusionlimited Aggregate a1842–18420 v641 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725500574nas a2200181 4500008003900000245005800039210005800097260002000155300001200175490004800187100002400235700001300259700001200272700001500284700001200299700002500311856005600336 1990 d00aMonte Carlo Method for Strongly Interacting Electrons0 aMonte Carlo Method for Strongly Interacting Electrons aMontréalc1990 a197-2100 vProceedings of Supercomputing Symposium '901 aTremblay, A.-M., S.1 aBoily, C1 aChen, L1 aNelisse, H1 aReid, A1 aPelletier, Dominique uhttps://www.physique.usherbrooke.ca/pages/node/755901925nas a2200133 4500008004100000245011600041210006900157300001400226490000700240520144800247100001601695700002401711856005601735 1990 eng d00aUniversal Multifractal Properties of Circle Maps From the Point-of-view of Critical Phenomena .1. Phenomenology0 aUniversal Multifractal Properties of Circle Maps From the Pointo a607–6370 v613 aThe strange attractor for maps of the circle at criticality has been shown to be characterized by a remarkable infinite set of exponents. This characterization by an infinite set of exponents has become known as the "multifractal" approach. The present paper reformulates the multifractal properties of the strange attractor in a way more akin to critical phenomena. This new approach allows one to study the universal properties of both the critical point and of its vicinity within the same framework, and it allows universal properties to be extracted from experimental data in a straightforward manner. Obtaining Feigenbaum's scalling function from the experimental data is, by contrast, much more difficult. In addition to the infinite set of exponents, universal amplitude ratios here appear naturally. To study the crossover region near criticality, a "correlation time," which plays a role analogous to the "correlation length" in critical phenomena, is introduced. This new approach is based on the introduction of a joint probability distribution for the positive integer moments of the closest-return distances. This joint probability distribution is physically motivated by the large fluctuations of the multifractal moments with respect to the choice of origin. The joint probability distribution has scaling properties analogous to those of the free energy close to a critical point.

1 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725302189nas a2200133 4500008004100000245012100041210006900162300001400231490000700245520170700252100001601959700002401975856005601999 1990 eng d00aUniversal Multifractal Properties of Circle Maps From the Point-of-view of Critical Phenomena .2. Analytical Results0 aUniversal Multifractal Properties of Circle Maps From the Pointo a639–6650 v613 aThe multifractal properties of maps of the circle exhibited in the preceding paper are analyzed from a simplified approach to the renormalization group of Kadanoff. This "second" renormalization group transformation, whose formulation and interpretation are discussed here, acts on the space of one-time-differentiable coordinate changes which associate a map on the critical manifold to the fixed point of the usual renormalization group. While the dependence of the multifractal moments on the starting point can be described statistically, and in particular through universal amplitude ratios as in paper I, it is shown that Fourier analysis is another possible approach. For all multifractal moments, the low-frequency Fourier coefficients have a universal self-similar scaling behavior analogous to that found for the usual spectrum of circle maps. In the case the first moment, it is demonstrated that the Fourier coefficients are, within constants, equal to the usual spectrum. The relation between amplitude ratios and Fourier coefficients is established and it is demonstrated that the universal values of the ratios come from the universal low-frequency Fourier coefficients. Since, for the universal ratios arising in the statistical description, the scaling regime is much more easily accessible than for the spectrum, the statistical approach described in paper I should be more convenient for experiments and could become an alternative to the usual spectral description. The universal statistical description of the multifractal moments adopted here is possible because the choice of the a priori probability for the starting point is demonstrated to be irrelevant.

1 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725400444nas a2200145 4500008004100000245005500041210005400096300001400150490000700164100001900171700001600190700001200206700002400218856005600242 1989 eng d00aFermi surface of the one-dimensional Hubbard model0 aFermi surface of the onedimensional Hubbard model a2297-23030 v401 aBourbonnais, C1 aNélisse, H1 aReid, A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/536900600nas a2200193 4500008003900000245007600039210006900115260000900184300001200193490002300205100001900228700001500247700001200262700002400274700001700298700001800315700001700333856005600350 1989 d00aFermi surface of the one-dimensional Hubbard model: Finite-size effects0 aFermi surface of the onedimensional Hubbard model Finitesize eff c1989 a805-8060 vPhysica C: 162-1641 aBourbonnais, C1 aNelisse, H1 aReid, A1 aTremblay, A.-M., S.1 aShelton, R N1 aHarrison, W A1 aPhilips, N E uhttps://www.physique.usherbrooke.ca/pages/node/755800482nas a2200145 4500008004100000245007600041210006900117300001200186490001200198100001900210700001500229700001200244700002400256856005600280 1989 eng d00aFermi surface of the one-dimensional Hubbard model: Finite-size effects0 aFermi surface of the onedimensional Hubbard model Finitesize eff a805-8060 v162-1641 aBourbonnais, C1 aNelisse, H1 aReid, A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/537000377nas a2200121 4500008004100000245004900041210004800090300001600138490000700154100002400161700001400185856005600199 1989 eng d00aFinite-size Effects In Continuum Percolation0 aFinitesize Effects In Continuum Percolation a5131–51390 v401 aTremblay, A.-M., S.1 aMACHTA, J uhttps://www.physique.usherbrooke.ca/pages/node/728300425nas a2200121 4500008004100000245007400041210006900115300001600184490000700200100001600207700002400223856005600247 1989 eng d00aInfinite Set of Crossover Exponents of the Xy Model and F(a) Approach0 aInfinite Set of Crossover Exponents of the Xy Model and Fa Appro a6819–68220 v391 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/725700434nas a2200145 4500008003900000245005600039210005500095260000900150300001100159490000800170100002400178700001600202700001400218856005600232 1989 d00aMultifractals and Noise in Metal-Insulator Mixtures0 aMultifractals and Noise in MetalInsulator Mixtures c1989 a89-1000 v1571 aTremblay, A.-M., S.1 aFourcade, B1 aBreton, P uhttps://www.physique.usherbrooke.ca/pages/node/755600549nas a2200181 4500008004100000245006600041210006600107300001600173490000700189100001500196700001800211700001400229700001600243700001600259700001200275700002400287856005600311 1989 eng d00aNegative Moments of Currents In Percolating Resistor Networks0 aNegative Moments of Currents In Percolating Resistor Networks a7318–73200 v401 aAharony, A1 aBlumenfeld, R1 aBreton, P1 aFourcade, B1 aHarris, A B1 aMeir, Y1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/722100624nas a2200193 4500008003900000245007900039210006900118250002700187260000900214300001200223490004100235100001600276700002400292700001500316700001400331700001400345700001500359856005600374 1988 d00aMultifractal analysis in the circle map: Analogies with critical phenomena0 aMultifractal analysis in the circle map Analogies with critical aSpringer-Verlag Berlin c1988 a183-1870 vSpringer Proceedings in Physics : 321 aFourcade, B1 aTremblay, A.-M., S.1 aJullien, R1 aPeliti, L1 aRammal, R1 aBoccara, N uhttps://www.physique.usherbrooke.ca/pages/node/755500576nas a2200157 4500008003900000245010700039210006900146260003100215300001200246490003200258100002400290700001600314700001900330700001300349856005600362 1988 d00aObservable infinite sets of exponents in multifractals and in critical phenomena: the role of symmetry0 aObservable infinite sets of exponents in multifractals and in cr aSaint-Adèle, Canadac1989 a137-1530 vWorld Scientific, Singapore1 aTremblay, A.-M., S.1 aFourcade, B1 aSaint-Aubin, Y1 aVinet, L uhttps://www.physique.usherbrooke.ca/pages/node/755700403nas a2200133 4500008003900000022001400039245005200053210004900105260001200154300001600166490000700182100002400189856005600213 1988 d a0319-197400aRenormalization group, fractals & multifractals0 aRenormalization group fractals multifractals c03/1988 a11-14/29-300 v211 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/757800426nas a2200121 4500008004100000245007500041210006900116300001400185490000700199100001800206700002400224856005600248 1988 eng d00aReply to Comment on the conductivity exponent in continuum percolation0 aReply to Comment on the conductivity exponent in continuum perco a7894-78950 v371 aLubensky, T C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/733100641nas a2200193 4500008003900000245008400039210006900123250002700192260002100219300001200240490004100252100002400293700001600317700001500333700001400348700001400362700001500376856005600391 1988 d00aUniversal properties of multifractal moments: Analogies with critical phenomena0 aUniversal properties of multifractal moments Analogies with crit aSpringer-Verlag Berlin aHeidelbergc1988 a176-1820 vSpringer Proceedings in Physics : 321 aTremblay, A.-M., S.1 aFourcade, B1 aJullien, R1 aPeliti, L1 aRammal, R1 aBoccara, N uhttps://www.physique.usherbrooke.ca/pages/node/755400426nas a2200121 4500008004100000245007700041210006900118300001400187490000700201100001600208700002400224856005600248 1987 eng d00aAnomalies in the multifractal analysis of self-similar resistor networks0 aAnomalies in the multifractal analysis of selfsimilar resistor n a2352-23580 v361 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732700490nas a2200145 4500008003900000245009000039210007000129260000900199300001200208490000800220100001800228700001800246700002400264856005600288 1987 d00aAntiferromagnétisme et champs cristallins dans les oxydes de cuivre supraconducteurs0 aAntiferromagnétisme et champs cristallins dans les oxydes de cui c1987 a757-7600 v3051 aAmbegaokar, V1 aDeGennes, P G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/755300464nas a2200121 4500008004100000245011300041210006900154300001400223490000700237100001800244700002400262856005600286 1987 eng d00aDensities of states, projected densities of states, and transfer-matrix methods from a unified point of view0 aDensities of states projected densities of states and transferma a1463-14740 v361 aLemieux, M -A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732800482nas a2200121 4500008003900000245005700039210005400096260003700150300001200187490008100199100002400280856005600304 1987 d00aElectrical properties of fractal networks (and why).0 aElectrical properties of fractal networks and why aPhiladelphie, Pennsylvaniec1987 a956-9590 vProceedings of the 1987 IEEE International Symposium on Circuits and Systems1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/755100466nas a2200145 4500008003900000245007200039210007100111260000900182300001200191490000700203100002400210700001600234700001400250856005600264 1987 d00aFamille d'exposants pour les propriétés électriques des fractals0 aFamille dexposants pour les propriétés électriques des fractals c1987 a183-2040 v111 aTremblay, A.-M., S.1 aFourcade, B1 aBreton, P uhttps://www.physique.usherbrooke.ca/pages/node/755000484nas a2200133 4500008004100000245010900041210006900150300001400219490000700233100001600240700001400256700002400270856005600294 1987 eng d00aMultifractals and critical phenomena in percolating networks: Fixed point, gap scaling, and universality0 aMultifractals and critical phenomena in percolating networks Fix a8925-89280 v361 aFourcade, B1 aBreton, P1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732900534nas a2200157 4500008003900000245004000039210003900079250003100118260002000149300001000169490008100179100002400260700001600284700002000300856005600320 1987 d00aNoise in metal-insulator composites0 aNoise in metalinsulator composites aWorld Scientific Singapore aMontréalc1987 a59-690 vProceedings of the 9th International Conference on Noise in Physical Systems1 aTremblay, A.-M., S.1 aFourcade, B1 aVliet, Van, C M uhttps://www.physique.usherbrooke.ca/pages/node/755200380nas a2200121 4500008004100000245005200041210005200093300001200145490000700157100001400164700002400178856005600202 1987 eng d00aResistance noise in nonlinear resistor networks0 aResistance noise in nonlinear resistor networks a415-4180 v581 aRammal, R1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/733000407nas a2200121 4500008004100000245006300041210006300104300001400167490000700181100001700188700002400205856005600229 1986 eng d00aAnomalous diffusion on fractal lattices with site disorder0 aAnomalous diffusion on fractal lattices with site disorder a2171-21810 v191 aRobillard, S1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731600466nas a2200121 4500008004100000245011800041210006900159300001200228490000800240100001600248700002400264856005600288 1986 eng d00aComment on the role of thermodynamic representations in the study of fluids in far from equilibrium steady states0 aComment on the role of thermodynamic representations in the stud a289-2930 v1351 aLlebot, J E1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731700410nas a2200121 4500008004100000245006500041210006500106300001400171490000700185100001600192700002400208856005600232 1986 eng d00aDiffusion noise of fractal networks and percolation clusters0 aDiffusion noise of fractal networks and percolation clusters a7802-78120 v341 aFourcade, B1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731800369nas a2200109 4500008004100000245005900041210005900100300001200159490000800171100002400179856005600203 1986 eng d00aDynamical phase transitions in hierarchical structures0 aDynamical phase transitions in hierarchical structures a329-3300 v1161 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732600494nas a2200133 4500008004100000245011800041210006900159300000800228490000700236100002400243700001300267700002400280856005600304 1986 eng d00aErratum: Splay rigidity in the diluted central-force elastic network (Physical Review Letters (1986) 57, 2 (274))0 aErratum Splay rigidity in the diluted centralforce elastic netwo a2740 v571 aTremblay, A.-M., S.1 aDay, A R1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732300422nas a2200121 4500008004100000245007100041210006900112300001400181490000700195100001800202700002400220856005600244 1986 eng d00aExpansion for transport exponents of continuum percolating systems0 aExpansion for transport exponents of continuum percolating syste a3408-34170 v341 aLubensky, T C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731900436nas a2200133 4500008004100000245006800041210006600109300001400175490000700189100002400196700001200220700001400232856005600246 1986 eng d00aExponents for 1/f noise, near a continuum percolation threshold0 aExponents for 1f noise near a continuum percolation threshold a2077-20800 v331 aTremblay, A.-M., S.1 aFeng, S1 aBreton, P uhttps://www.physique.usherbrooke.ca/pages/node/732000417nas a2200121 4500008004100000245006400041210006300105300001400168490000700182100002600189700002400215856005600239 1986 eng d00aLight scattering spectrum of one-dimensional mixed crystals0 aLight scattering spectrum of onedimensional mixed crystals a6599-66110 v331 aLopez Castillo, J M L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732100383nas a2200121 4500008004100000245004800041210004800089300001400137490000700151100002300158700002400181856005600205 1986 eng d00aLinewidths from sum rules in mixed crystals0 aLinewidths from sum rules in mixed crystals a8482-84850 v341 aLopezcastillo, J M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732200414nas a2200133 4500008004100000245005100041210005000092300001400142490000700156100001300163700002400176700002400200856005600224 1986 eng d00aRigid Backbone: A New Geometry for Percolation0 aRigid Backbone A New Geometry for Percolation a2501-25040 v561 aDay, A R1 aTremblay, A.-M., S.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732400435nas a2200133 4500008004100000245006400041210006300105300000900168490000700177100002400184700001300208700002400221856005600245 1986 eng d00aSplay rigidity in the diluted central-force elastic network0 aSplay rigidity in the diluted centralforce elastic network a14250 v561 aTremblay, A.-M., S.1 aDay, A R1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/732500450nas a2200133 4500008004100000245007600041210006900117300001400186490000700200100001400207700001500221700002400236856005600260 1985 eng d00a1/f noise in random resistor networks: Fractals and percolating systems0 a1f noise in random resistor networks Fractals and percolating sy a2662-26710 v311 aRammal, R1 aTannous, C1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731200459nas a2200133 4500008004100000245008600041210007000127300000900197490000700206100001400213700001800227700002400245856005600269 1985 eng d00aComment on {``$ε$ expansion for the conductivity of a random resistor network''}0 aComment on ε expansion for the conductivity of a random resistor a10870 v541 aRammal, R1 aLemieux, M -A1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731300477nas a2200145 4500008004100000245007700041210006900118300001400187490000700201100001400208700001500222700001400237700002400251856005600275 1985 eng d00aFlicker (1f) noise in percolation networks: A new hierarchy of exponents0 aFlicker 1f noise in percolation networks A new hierarchy of expo a1718-17210 v541 aRammal, R1 aTannous, C1 aBreton, P1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731400394nas a2200121 4500008004100000245006100041210006000102300001000162490000800172100001200180700002400192856005600216 1985 eng d00aLong-range correlations for diffusion in a random medium0 aLongrange correlations for diffusion in a random medium a33-350 v1111 aRubi, M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731500450nas a2200133 4500008004100000245007000041210006900111300001200180490000700192100001300199700002400212700002400236856005600260 1985 eng d00aSpectral properties of percolating central force elastic networks0 aSpectral properties of percolating central force elastic network a245-2510 v751 aDay, A R1 aTremblay, A.-M., S.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731100534nas a2200145 4500008003900000245014300039210006900182260000900251300001000260490000700270100001700277700001400294700002400308856005600332 1985 d00aUnified Approach to Numerical Transfer Matrix Methods for Disordered Systems: Applications to Mixed Crystals and to Elasticity Percolation0 aUnified Approach to Numerical Transfer Matrix Methods for Disord c1985 aL1-L70 v461 aLemieux, M A1 aBreton, P1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/754900430nas a2200157 4500008003900000245003800039210003600077260000900113300001600122490000700138100001500145700002400160700001500184700001700199856005600216 1984 d00aA.C. Response of Fractal Networks0 aAC Response of Fractal Networks c1984 aL-913/11-120 v451 aClerc, J P1 aTremblay, A.-M., S.1 aAlbinet, G1 aMitescu, C D uhttps://www.physique.usherbrooke.ca/pages/node/754200419nas a2200121 4500008004100000245007300041210006600114300001200180490000800192100001700200700002400217856005600241 1984 eng d00aOn the linear specific heat of disordered solids at low temperatures0 alinear specific heat of disordered solids at low temperatures a245-2460 v1021 aDandoloff, R1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/731000576nas a2200145 4500008004100000245017100041210006900212300001400281490000700295100001700302700001500319700001600334700002400350856005600374 1984 eng d00aLiquid-expanded liquid-condensed phase transition in amphiphilic monolayers: A renormalization-group approach to chiral-symmetry breaking of hydrocarbon-chain defects0 aLiquidexpanded liquidcondensed phase transition in amphiphilic m a2720-27290 v301 aLegré, J -P1 aAlbinet, G1 aFirpo, J -L1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730800582nas a2200169 4500008003900000245011000039210006900149260000900218300001000227490002700237100001600264700002400280700001900304700001500323700001800338856005600356 1984 d00aNonequilibrium Phonon Distribution in a Quantizing Magnetic Field: A Tunable GHz to THz Phonon Generator?0 aNonequilibrium Phonon Distribution in a Quantizing Magnetic Fiel c1984 a49/510 vSpringer-Verlag Berlin1 aSlater, G W1 aTremblay, A.-M., S.1 aEisenmenger, W1 aLaBmann, K1 aDöttinger, S uhttps://www.physique.usherbrooke.ca/pages/node/754700456nas a2200121 4500008004100000245010900041210006900150300001400219490000700233100002400240700001400264856005600278 1984 eng d00aPosition-space rescaling and hierarchical lattice models of disordered one-dimensional systems (invited)0 aPositionspace rescaling and hierarchical lattice models of disor a2389-23940 v551 aTremblay, A.-M., S.1 aBreton, P uhttps://www.physique.usherbrooke.ca/pages/node/730700461nas a2200157 4500008003900000245004400039210004400083260000900127300001200136490002700148100002400175700002400199700001100223700001300234856005600247 1984 d00aTheories of Nonequilibrium Fluctuations0 aTheories of Nonequilibrium Fluctuations c1984 a267-3150 vSpringer-Verlag Berlin1 aTremblay, A.-M., S.1 aCasas-Vàsquez, J S1 aJou, D1 aLebon, G uhttps://www.physique.usherbrooke.ca/pages/node/754300426nas a2200121 4500008004100000245007700041210006900118300001400187490000700201100001600208700002400224856005600248 1984 eng d00aTunable quantum hypersound generator in the gigahertz to terahertz range0 aTunable quantum hypersound generator in the gigahertz to teraher a2289-22920 v291 aSlater, G W1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730900441nas a2200121 4500008004100000245009300041210006900134300001400203490000700217100001500224700002400239856005600263 1983 eng d00aChain fusion and orientational ordering in monomolecular layers of amphiphilic molecules0 aChain fusion and orientational ordering in monomolecular layers a2206-22160 v271 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730300482nas a2200133 4500008004100000245010200041210006900143300001200212490000700224100001900231700002400250700001800274856005600292 1983 eng d00aChaotic scaling trajectories and hierarchical lattice models of disordered binary harmonic chains0 aChaotic scaling trajectories and hierarchical lattice models of a218-2310 v281 aLanglois, J -M1 aTremblay, A.-M., S.1 aSouthern, B W uhttps://www.physique.usherbrooke.ca/pages/node/730400420nas a2200121 4500008004100000245007400041210006900115300001200184490000700196100001500203700002400218856005600242 1983 eng d00aDisordered binary harmonic chains with site-dependent force constants0 aDisordered binary harmonic chains with sitedependent force const a232-2350 v281 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730500550nas a2200169 4500008003900000245006900039210006900108260000900177300001000186490003700196100002400233700002100257700001500278700001300293700001800306856005600324 1983 d00aFluctuations in Dissipative Steady States of Thin Metallic Films0 aFluctuations in Dissipative Steady States of Thin Metallic Films c1983 a53-550 vElsevier Science Publishers B.V.1 aTremblay, A.-M., S.1 aVidal, François1 aSavelli, M1 aLecoy, G1 aNougier, J -P uhttps://www.physique.usherbrooke.ca/pages/node/754800489nas a2200145 4500008004100000245008500041210006900126300001400195490000700209100001800216700001500234700001400249700002400263856005600287 1983 eng d00aReal-space rescaling method for the spectral properties of tight-binding systems0 aRealspace rescaling method for the spectral properties of tightb a1405-14080 v271 aSouthern, B W1 aKumar, A A1 aLoly, P D1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730600467nas a2200133 4500008003900000245009600039210006900135260000900204300001500213490000700228100002400235700001800259856005600277 1983 d00aScalling and Density of States of Fractal Lattices form a Generating Function Point of View0 aScalling and Density of States of Fractal Lattices form a Genera c1983 aL-843/1-100 v441 aTremblay, A.-M., S.1 aSouthern, B W uhttps://www.physique.usherbrooke.ca/pages/node/754100521nas a2200133 4500008003900000245009900039210007100138260003300209300001000242490004000252100001500292700002400307856005600331 1982 d00aApplication du groupe de renormalisation à l'étude des monocouches de molécules amphiphiles0 aApplication du groupe de renormalisation à létude des monocouche aIle des Embiez, Francec1983 a16-230 vPhysique des surfaces et interfaces1 aAlbinet, G1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/754000415nas a2200121 4500008004100000245006900041210006900110300001400179490000700193100002400200700001300224856005600237 1982 eng d00aFluctuations in dissipative steady states of thin metallic films0 aFluctuations in dissipative steady states of thin metallic films a7562-75760 v251 aTremblay, A.-M., S.1 aVidal, F uhttps://www.physique.usherbrooke.ca/pages/node/730200439nas a2200121 4500008004100000245008200041210006900123300001400192490000700206100002400213700002400237856005600261 1982 eng d00aThermal fluctuations in the presence of two dissipative steady-state currents0 aThermal fluctuations in the presence of two dissipative steadyst a1692-16980 v251 aTremblay, A.-M., S.1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/730100424nas a2200121 4500008004100000245007900041210006900120300001200189490000700201100001400208700002400222856005600246 1981 eng d00aDeviation of 1/f voltage fluctuations from scale-similar Gaussian behavior0 aDeviation of 1f voltage fluctuations from scalesimilar Gaussian a253-2680 v251 aNelkin, M1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/729700358nas a2200121 4500008004100000245004000041210004000081300001400121490000700135100002400142700001400166856005600180 1981 eng d00aEquilibrium resistance fluctuations0 aEquilibrium resistance fluctuations a2551-25660 v241 aTremblay, A.-M., S.1 aNelkin, M uhttps://www.physique.usherbrooke.ca/pages/node/730000487nas a2200133 4500008004100000245011400041210006900155300001400224490000700238100002400245700001200269700001600281856005600297 1981 eng d00aErratum: Fluctuations about simple nonequilibrium steady states (Physical Review A (1981) 24, 3, (1655-1656))0 aErratum Fluctuations about simple nonequilibrium steady states P a1655-16560 v241 aTremblay, A.-M., S.1 aArai, M1 aSiggia, E D uhttps://www.physique.usherbrooke.ca/pages/node/729800422nas a2200133 4500008004100000245005900041210005900100300001400159490000700173100002400180700001200204700001600216856005600232 1981 eng d00aFluctuations about simple nonequilibrium steady states0 aFluctuations about simple nonequilibrium steady states a1451-14800 v231 aTremblay, A.-M., S.1 aArai, M1 aSiggia, E D uhttps://www.physique.usherbrooke.ca/pages/node/729900430nas a2200133 4500008004100000245006500041210006500106300001000171490000700181100002400188700001600212700001200228856005600240 1980 eng d00aFluctuations about hydrodynamic nonequilibrium steady states0 aFluctuations about hydrodynamic nonequilibrium steady states a57-600 v761 aTremblay, A.-M., S.1 aSiggia, E D1 aArai, M uhttps://www.physique.usherbrooke.ca/pages/node/729600488nas a2200145 4500008003900000245008700039210006900126260000900195300001300204490000800217100002400225700002100249700001600270856005600286 1980 d00aKinetic Equations in Superconductors and the Nature and Decay Rate of the New Mode0 aKinetic Equations in Superconductors and the Nature and Decay Ra c1980 a401/1-480 v1241 aTremblay, A.-M., S.1 aPatton, Bruce, R1 aMartin, P C uhttps://www.physique.usherbrooke.ca/pages/node/752200600nas a2200133 4500008003900000245007800039210006900117260004100186300001200227490013300239100002400372700001400396856005600410 1980 d00aStability of nonequilibrium superconducting states I : General principles0 aStability of nonequilibrium superconducting states I General pri aAcqua Fredda di Maratea, Italyc1981 a289-3070 vProceedings of the NATO Advanced Study Institute on Nonequilibrium Superconductivity, Phonons and Kapitza Boundaries Chapter 101 aTremblay, A.-M., S.1 aGray, K E uhttps://www.physique.usherbrooke.ca/pages/node/753800573nas a2200133 4500008003900000245008300039210006900122260000900191300001200200490013300212100002400345700001400369856005600383 1980 d00aStability of nonequilibrium superconducting states II : Theory and Experiments0 aStability of nonequilibrium superconducting states II Theory and c1981 a309-3400 vProceedings of the NATO Advanced Study Institute on Nonequilibrium Superconductivity, Phonons and Kapitza Boundaries Chapter 111 aTremblay, A.-M., S.1 aGray, K E uhttps://www.physique.usherbrooke.ca/pages/node/753900458nas a2200133 4500008004100000245007800041210006900119300001400188490000700202100001900209700001600228700002400244856005600268 1980 eng d00aSystematics of Carnot cycles at positive and negative Kelvin temperatures0 aSystematics of Carnot cycles at positive and negative Kelvin tem a1063-10740 v131 aLandsberg, P T1 aTykodi, R J1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/729500478nas a2200121 4500008004100000245012700041210006900168300001400237490000700251100002400258700001800282856005600300 1979 eng d00aEigenmodes of the coupled two-dimensional Wigner-crystal-liquid-surface system and instability of a charged liquid surface0 aEigenmodes of the coupled twodimensional Wignercrystalliquidsurf a2190-21950 v201 aTremblay, A.-M., S.1 aAmbegaokar, V uhttps://www.physique.usherbrooke.ca/pages/node/729400536nas a2200145 4500008003900000245013600039210006900175260000900244490000700253100002400260700001600284700001600300700001800316856005600334 1979 d00aMicroscopic Calculation of the Nonlinear Current Fluctuations of a Metallic Resistor: the Problem of Heating in Perturbation Theory0 aMicroscopic Calculation of the Nonlinear Current Fluctuations of c19790 v191 aTremblay, A.-M., S.1 aPatton, B R1 aMartin, F C1 aMaldague, P F uhttps://www.physique.usherbrooke.ca/pages/node/750100417nas a2200121 4500008003900000245007400039210006900113260000900182490000700191100001700198700002400215856005600239 1979 d00aNonequilibrium Superconducting States with Two Coexisting Energy Gaps0 aNonequilibrium Superconducting States with Two Coexisting Energy c19790 v421 aSchön, Gerd1 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/750000603nas a2200181 4500008003900000245009900039210006900138260000900207300001200216490002600228100002400254700001700278700001600295700002100311700001900332700001400351856005600365 1979 d00aTunnel Injection Induced Nonequilibrium Superconducting States with two Coexisting Energy Gaps0 aTunnel Injection Induced Nonequilibrium Superconducting States w c1980 a319-3240 vBerkeley Springs # 581 aTremblay, A.-M., S.1 aSchön, Gerd1 aGubser, D U1 aFrancavilla, T L1 aLeibowitz, J R1 aWolf, S A uhttps://www.physique.usherbrooke.ca/pages/node/753600395nas a2200109 4500008003900000245008100039210006900120260000900189490000700198100002400205856005600229 1976 d00aComment on : Negative Kelvin Temperatures : Some Anomalies and a Speculation0 aComment on Negative Kelvin Temperatures Some Anomalies and a Spe c19760 v441 aTremblay, A.-M., S. uhttps://www.physique.usherbrooke.ca/pages/node/749900394nas a2200121 4500008004100000245005800041210005700099300001400156490000700170100002400177700001500201856005600216 1975 eng d00aNonadditive forces and vacancies in rare-gas crystals0 aNonadditive forces and vacancies in raregas crystals a1728-17310 v111 aTremblay, A.-M., S.1 aGlyde, H R uhttps://www.physique.usherbrooke.ca/pages/node/7293