Metallization and superconductivity in doped metal-oxide layered compounds

Abstract

A new approach is proposed to the problem of the superconducting state in layered metal-oxide materials, essentially using the fact that the concentration of charge carriers in them is equal to the concentration of chaotically located scatterers (charged dopants). Self-consistent conditions on chemical potential and superconducting gap parameter are written in terms of the averages of electronic Green functions, which also take into account the intrinsic disorder. The resulting closed set of dynamical equations permits, in principle, a complete description of the disordered electronic system in the presence of superconducting pairing. At T = 0, different (insulating, metallic and superconducting) phase states are determined, depending on the values of the doping x, and the scattering-to-pairing ratio, y. In particular, this explains the bell-shaped T c( x), characteristic of many high- T c superconductors.