Density of states in a superconductor carrying a supercurrent

TL;DR

This study measures how a supercurrent affects the electronic density of states in a superconductor, revealing a reduction in the superconducting gap similar to effects caused by an external magnetic field.

Contribution

It provides experimental validation of theoretical predictions on the influence of supercurrents on the DOS in diffusive superconductors.

Findings

Supercurrent weakens pair correlations in the superconductor.

The DOS modification due to supercurrent resembles that caused by magnetic fields.

Superconducting gap is reduced under supercurrent conditions.

Abstract

We have measured the tunneling density of states (DOS) in a superconductor carrying a supercurrent or exposed to an external magnetic field. The pair correlations are weakened by the supercurrent, leading to a modification of the DOS and to a reduction of the gap. As predicted by the theory of superconductivity in diffusive metals, we find that this effect is similar to that of an external magnetic field.