Proximity-induced superconductivity in nanowires: Mini-gap state and differential magnetoresistance oscillations

TL;DR

This paper investigates proximity-induced superconductivity in gold nanowires, revealing a mini-gap phase and oscillations in magnetoresistance, with a theoretical model explaining the coexistence of superconducting and normal regions.

Contribution

It introduces the concept of a mini-gap phase in nanowires and provides a theoretical framework for understanding oscillations in magnetoresistance due to proximity effects.

Findings

Short nanowires show sharp superconducting transitions.

Long nanowires exhibit nonzero resistance.

Intermediate lengths display a mini-gap phase with two sharp transitions.

Abstract

We study proximity-induced superconductivity in gold nanowires as a function of the length of the nanowire, magnetic field, and excitation current. Short nanowires exhibit a sharp superconducting transition, whereas long nanowires show nonzero resistance. At intermediate lengths, however, we observe two sharp transitions; the normal and superconducting regions are separated by what we call the mini-gap phase. Additionally, we detect periodic oscillations in the differential magnetoresistance. We provide a theoretical model for the mini-gap phase as well as the periodic oscillations in terms of the coexistence of proximity-induced superconductivity with a normal region near the center of the wire, created either by temperature or application of a magnetic field.