Extended Hubbard model applied to study the pressure effects in high-temperature superconductors

E. V. L. DE MELLO; C. ACHA

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 1997 vol. 56 p. 466 - 469

1098-0121

We make use of a BCS-type approach based on the extended Hubbard Hamiltonian to study the superconductor transition and to give a microscopic interpretation of the pressure effects on Tc in high-temperature superconductors. This method suggests that the applied pressure causes an increase of the superconducting gap and this effect is explored in order to explain the variations of Tc. Our approach is therefore beyond the scope of previous phenomenological models which basically postulate a pressure-induced charge transfer and an intrinsic term linear in pressure. We obtain a microscopic interpretation of this intrinsic term and a general expansion of Tc in terms of the pressure. To demonstrate the efficiency of the method we apply it to the experimental data of the Hg-based superconductors.