Vortices in a cylinder: Localization after depinning

TL;DR

This paper investigates vortex localization near the edges of a hollow superconducting cylinder with defects, revealing a semiclassical description of vortex bunching and phase transitions akin to random matrix models.

Contribution

It introduces a semiclassical model explaining vortex localization and density singularities near edges after depinning in superconducting cylinders.

Findings

Vortices form dense bunches near edges after depinning.

Vortex density exhibits square root singularity at bunch borders.

Tuning current strength leads to different singular regimes.

Abstract

Edge effects in the depinned phase of flux lines in hollow superconducting cylinder with columnar defects and electric current along the cylinder are investigated. Far from the ends of the cylinder vortices are distributed almost uniformly (delocalized). Nevertheless, near the edges these free vortices come closer together and form well resolved dense bunches. A semiclassical picture of this localization after depinning is described. For a large number of vortices their density $\rho(x)$ has square root singularity at the border of the bunch ($\rho(x)$ is semicircle in the simplest case). However, by tuning the strength of current, the various singular regimes for $\rho(x)$ may be reached. Remarkably, this singular behaviour reproduces the phase transitions discussed during the past decade within the random matrix regularization of 2d-Gravity.