Insulators, metals, pseudogaps and high-temperature superconductors

Rutgers University, NJ, USA
date: 
mar, 01/24/2012
Undefined
presentation: 

Strong repulsion between electrons in a half-filled band leads to an insulating state, the Mott insulator. Unexpectedly, strong repulsion can also lead to superconductivity. For example, in layered organic superconductors, increasing pressure transforms the insulator into a superconductor. The situation is more complicated in doped Mott insulators, such as high-temperature superconductors. To elucidate the influence of Mott Physics away from half-filling, we exhibit the normal-state phase diagram as a function of temperature, interaction strength and filling. We use cellular dynamical mean-field theory on a plaquette and continuous-time quantum Monte Carlo methods. This methodology leads to a new point of view that replaces Landau Fermi liquid theory when interactions are strong. It is found that upon increasing filling towards the insulator, there is a surface of first-order transition between two metals at nonzero doping, a Fermi liquid and a pseudogapped metal. Finite temperature signatures of this transition seem to be what controls the strange metal appearing in underdoped high-temperature superconductors. [1-3] The pseudogap temperature appears as a Widom line.[4] The superconducting state can also be studied with the same methodology. [6-7] I will spend a fair amount of time to discuss our latest work on this topic.
References:
[1] G. Sordi, K. Haule, and A.-M. S. Tremblay, Phys. Rev. Lett. 104, 226402 (2010)
[2] G. Sordi, K, Haule, and A.-M.S. Tremblay,  Phys. Rev. B. 84 075161 (2011)
[3] S. Okamoto, D. Sénéchal, M. Civelli, and A.-M. S. Tremblay, Phys. Rev. B 82, 180511(R) (2010)
[4] G. Sordi,P. Sémon, K, Haule, and A.-M.S. Tremblay, arXiv:1110.1392
[5] B. Kyung, D. Sénéchal and A.-M.S., Tremblay, Phys. Rev. B 80, 205109 (2009)
[6] S. S. Kancharla, M. Civelli, M. Capone, B. Kyung, D. Sénéchal, G. Kotliar, A.-M.S. Tremblay Phys. Rev. B 77, 184516 (2008)
[7] G. Sordi,P. Sémon, K, Haule, and A.-M.S. Tremblay, arXiv:1201.1283v1