Andreev scattering in nanoscopic junctions at high magnetic fields

TL;DR

This study investigates Andreev resonances in atomic-scale Pb contacts under high magnetic fields, revealing how superconductivity persists in a mesoscopic region and aligns with theoretical predictions.

Contribution

It provides the first detailed experimental analysis of Andreev scattering in nanoscopic junctions at high magnetic fields, including a quantitative comparison with theory.

Findings

Observation of multiple Andreev resonances at high magnetic fields

Superconductivity persists in a mesoscopic region near the contact

Good agreement between experimental data and theoretical models

Abstract

We report on the measurement of multiple Andreev resonances at atomic size point contacts between two superconducting nanostructures of Pb under magnetic fields higher than the bulk critical field, where superconductivity is restricted to a mesoscopic region near the contact. The small number of conduction channels in this type of contacts permits a quantitative comparison with theory through the whole field range. We discuss in detail the physical properties of our structure, in which the normal bulk electrodes induce a proximity effect into the mesoscopic superconducting part.