Dynamically current-driven de Gennes -St James states in Metal-Superconductor junctions

TL;DR

This paper studies how current-induced destruction of superconductivity in a junction creates bound states that cause conductance oscillations, affecting the interpretation of experimental data in certain superconductors.

Contribution

It introduces a model for voltage-dependent de Gennes-Saint James states in NN'S junctions and analyzes their impact on conductance measurements.

Findings

Voltage-dependent bound states lead to distinct conductance oscillations.

These effects are significant in materials with high Fermi velocities like pnictides.

Implications for identifying bosonic modes in strongly coupled superconductors.

Abstract

We investigate the conductance of a Normal-Normal'-Superconductor (NN'S) junction, in which current injection destroys superconductivity in a small region N' of the superconductor, with a size varying with the applied voltage V. Voltage-dependent de Gennes-Saint James (dGSJ) bound states appearing in the N' slab lead to two distinct sets of conductance oscillations. We show that this effect significantly alters the conductance of systems for which $\kappa^2v_F \sim 10^9$ m/s such as pnictides ($\kappa$ and $v_F$ being the Ginzburg number and the Fermi velocity, respectively), and we discuss their consequences on the identification of the bosonic modes of strongly coupled superconductors.