Dephasing in disordered metals with superconductive grains

TL;DR

This paper investigates how superconductive grains in a disordered metal affect electron dephasing, revealing a nearly temperature-independent dephasing contribution and deviations from classical theory.

Contribution

It provides a theoretical calculation of electron dephasing time considering superconductive grains, highlighting effects above the superconducting transition.

Findings

Dephasing rate is nearly temperature-independent due to Andreev reflection.

Dephasing exceeds classical predictions across a broad temperature range.

Magnetoresistance is positive and dominated by Maki-Tompson correction in two dimensions.

Abstract

Temperature dependence of electron dephasing time $\tau_\phi(T)$ is calculated for a disordered metal with small concentration of superconductive grains. Above the macroscopic superconducting transition line, when electrons in the metal are normal, Andreev reflection from the grains leads to a nearly temperature-independent contribution to the dephasing rate. In a broad temperature range $1/\tau_phi(T)$ strongly exceeds the prediction of the classical theory of dephasing in normal disordered conductors, whereas magnetoresistance is dominated (in two dimensions) by the Maki-Tompson correction and is positive.