Evl. Demello et C. Acha, EXTENDED HUBBARD-MODEL APPLIED TO STUDY THE PRESSURE EFFECTS IN HIGH-TEMPERATURE SUPERCONDUCTORS, Physical review. B, Condensed matter, 56(1), 1997, pp. 466-469
We make use of a BCS-type approach based on the extended Hubbard Hamil
tonian to study the superconductor transition and to give a microscopi
c interpretation of the pressure effects on T-c in high-temperature su
perconductors. This method suggests that the applied pressure causes a
n increase of the superconducting gap and this effect is explored in o
rder to explain the variations of T-c. Our approach is therefore beyon
d the scope of previous phenomenological models which basically postul
ate a pressure-induced charge transfer and an intrinsic term linear in
pressure. We obtain a microscopic interpretation of this intrinsic te
rm and a general expansion of T-c in terms of the pressure. To demonst
rate the efficiency of the method we apply it to the experimental data
of the Hg-based superconductors.