Electronic Structure and Transition Temperature of thed-pModel

Abstract

The dressed d -electron Green's function of the d - p model is computed self-consistently based on the fluctuation-exchange approximation. Using this Green's function and assuming the d _{x ² - y ²} symmetry for the momentum dependence of the gap function, we obtain the reasonable superconducting transition temperature T _c in the several cases where the d -( p -)hole number is close to the experimental value of La _1.76 Sr _0.24 CuO ₄ based on NMR/NQR analyses. Using this Green's function, we calculate the d -electron spin susceptibility, which has very sharp incommensurate peaks near T _c for the low frequency as observed in neutron scattering data on La _1.86 Sr _0.14 CuO ₄ . The quasi-particle excitation spectrum in the normal state near T _c is also obtained from this Green's function. The energy dispersion of quasi-particles near the Fermi level is almost flat around the (π/ a ,0) point. This electronic structure is due to many-body effects, rather than being induced by band effects.