Analysis of Superconductivity in d-p Model on Basis of Perturbation Theory
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We investigate the mass enhancement factor and the superconducting transition temperature in the d-p model for the high-T_c cuprates. We solve the Eliashberg equation using the third-order perturbation theory with respect to the on-site Coulomb repulsion U. We find that when the energy difference between the d-level and p-level is large, the mass enhancement factor becomes large and T_c tends to be suppressed owing to the difference of the density of state for d-electron at the Fermi level. From another viewpoint, when the energy difference is large, the d-hole number approaches unity and the electron correlation becomes strong and enhances the effective mass. This behavior for the electron number is the same as that for the f-electron number in the heavy fermion systems. The mass enhancement factor plays an essential role in understanding the difference in T_c between the LSCO and YBCO systems.
- Journal of the Physical Society of Japan
Journal of the Physical Society of Japan 74(5), 1397-1400, 2005-05
The Physical Society of Japan (JPS)