A 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/728700627nas 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/7560