Quasiparticle current in ballistic NcS'S junctions

TL;DR

This paper develops a theoretical model for quasiparticle current in ballistic NcS'S junctions, generalizing the BTK model to inhomogeneous, disordered S'S electrodes and relating current to the energy spectrum of the proximity sandwich.

Contribution

It introduces a generalized model for inhomogeneous S'S electrodes in NcS'S junctions, linking quasiparticle current to the energy spectrum in disordered conditions.

Findings

Relation between quasiparticle current and energy spectrum established

Model applicable for arbitrary parameters of S' and S materials

Generalizes the BTK model for inhomogeneous electrodes

Abstract

Nonstationary properties of ballistic constrictions $NcS^{\prime}S$ with disordered $S^{\prime}S$ electrodes are analyzed theoretically. Amplitudes of Andreev and normal reflections at the constriction are related to the solutions of a stationary Green function problem in an inhomogeneous $% S^{\prime}S$ electrode in a dirty limit. This provides a generalization of the model of Blonder, Tinkham and Klapwijk for a spatially inhomogeneous case. The relation between quasiparticle current in $NcS^{\prime}S$ junctions and energy spectrum of a $S^{\prime}S$ proximity sandwich is found for arbitrary parameters of $S^{\prime}$ and $S$ materials and of $% S^{\prime}S$ interface.