Proximity Effect and Multiple Andreev Reflections in Diffusive SNS Junctions

TL;DR

This paper develops a theoretical framework for understanding the current-voltage behavior in diffusive SNS junctions, highlighting the roles of proximity effect and multiple Andreev reflections in shaping conductance features.

Contribution

It introduces a solution to the time-dependent Usadel equations for arbitrary normal wire length, elucidating phase-coherent transport mechanisms in SNS junctions.

Findings

Proximity effect and Andreev reflections create complex subgap conductance structures.

The theory explains non-equilibrium distribution functions in these junctions.

Results are applicable to designing superconducting electronic devices.

Abstract

We present a theory of the current-voltage characteristics in diffusive superconductor-normal-metal-superconductor junctions. By solving the time-dependent Usadel equations we are able to describe the phase-coherent transport for arbitrary length of the normal wire. We show how the interplay between proximity effect and multiple Andreev reflections gives rise to a rich subgap structure in the conductance and how it is revealed in the non-equilibrium distribution function.