Thermally Assisted Penetration and Exclusion of Single Vortex in Mesoscopic Superconductors

TL;DR

This paper investigates how thermal fluctuations influence the entry and exit of a single vortex in mesoscopic superconductors, providing a framework to predict and measure vortex behavior under thermal activation.

Contribution

It introduces a method to calculate the distribution of vortex penetration and exclusion fields considering thermal activation in mesoscopic superconductors.

Findings

Distribution of penetration and exclusion fields derived

Thermal fluctuations enable vortex crossing even below surface barrier

Quantitative predictions align with potential experimental measurements

Abstract

A single vortex overcoming the surface barrier in a mesoscopic superconductor with lateral dimensions of several coherence lengths and thickness of several nanometers provides an ideal platform to study thermal activation of a single vortex. In the presence of thermal fluctuations, there is non-zero probability for vortex penetration into or exclusion from the superconductor even when the surface barrier does not vanish. We consider the thermal activation of a single vortex in a mesoscopic superconducting disk of circular shape. To obtain statistics for the penetration and exclusion magnetic fields, slow and periodic magnetic fields are applied to the superconductor. We calculate the distribution of the penetration and exclusion fields from the thermal activation rate. This distribution can also be measured experimentally, which allows for a quantitative comparison.