Density of States in Superconductor - Normal Metal - Superconductor Junctions

TL;DR

This paper investigates how the phase difference between two superconductors affects the density of states in a superconductor-normal metal-superconductor junction, revealing a phase-dependent energy gap that closes at pi.

Contribution

It provides analytical and numerical analysis of the phase dependence of the density of states in SNS junctions without electron-electron interactions.

Findings

Energy gap decreases with increasing phase difference

Gap closes at phase difference of pi

Analytical and numerical results are consistent

Abstract

We consider the chi_0 dependence of the density of states inside the normal metal of a superconductor - normal metal - superconductor (SNS) junction.Here chi_0 is the phase difference of two superconductors of the junction. It is shown that in the absence of electron-electron interaction the energy dependence of the density of states has a gap which decreases as chi_0 increases and closes at chi_0= pi. Both the analytical expressions for the chi_0 dependence of the density of states and the results of numerical simulations are presented.