The Hubbard model applied to the phase diagram and pressure effects in YBa₂Cu₃O_7-δ superconductors

2001/06/19 by E. S. Caixeiro, Caixeiro, E. S., E. V. L. de Mello +1
Physics and Astronomy · #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con

paper · pdf · doi:10.48550/arxiv.cond-mat/0106382

submitted to Phys. Rev. B

arxiv created 2001/06/19 · arxiv updated 2009/11/30

Abstract

We apply a method based on a BCS-type approach to the extended Hubbard model to deal with the YBa₂Cu₃O_7-δ superconductor family under pressure. The parameters of the tight-binding band are taken from experiments, and the coupling strength U and V are estimated from the zero pressure phase diagram Tc X n_h, where n_h is the hole content and Tc the critical temperature. With the assumption that the pressure P modifies the magnitude V of the attractive potential besides n_h, we obtain a general expansion of Tc in terms of the pressure P, as Tc(P)=Tc(n_h(P),V(P)). With this we can distinguish the charge transfer and the intrinsic contribution to Tc. We show that the changes of Tc with P for YBa₂Cu₃O_7-δ are almost due to the intrinsic term.

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