Local density of states of normal-superconducting proximity contact systems with arbitrary concentration of impurities

Abstract

The superconducting order induced in the normal layer by the proximity effect has considerable influence on the density of states of the normal layer. Belzig et al. reported that, when the normal layer is thin, a mini-gap in the density of states appears in the dirty limit. We study the local density of states of normal-superconducting proximity contact systems with arbitrary concentration of impurities by quasi-classical Green's function method. It is found that the local density of states has also a mini-gap at intermediate concentrations of impurities. The mean free path dependence of the mini-gap is reported.