Theory of the "universal" degradation of T in high-temperature superconductors

Abstract

The superconducting T_c decreases similarly with disorder (as measured by resistivity ρ ) for all systems with high T_c. We propose that this is a localization effect. For strong disorder, electron diffusion is slow and strongly scale dependent. This increases the effective Coulomb repulsion. Model calculations with realistic parameters describe well the experimental T_c-vs-ρ curves. Explanations are suggested for the relatively large critical conductance found.