Metastability and paramagnetism in superconducting mesoscopic disks

TL;DR

This paper investigates the energy landscape and metastability phenomena in superconducting mesoscopic disks using a projected order parameter within the Ginzburg-Landau framework, revealing vortex configuration stability and supercurrent behavior.

Contribution

It introduces a method to calculate local minima, saddle points, and energy barriers, providing new insights into vortex states and supercurrent reversal in mesoscopic superconductors.

Findings

Identification of local minima and saddle points in energy landscape.

Supercurrent reversal occurs before vortex escape at decreasing magnetic fields.

Analysis of vortex configuration stability and energy barriers.

Abstract

A projected order parameter is used to calculate, not only local minima of the Ginzburg-Landau energy functional, but also saddle points or energy barriers responsible for the metastabilities observed in superconducting mesoscopic disks (Geim et al. Nature {\bf 396}, 144 (1998)). We calculate the local minima magnetization and find the energetic instability points between vortex configurations with different vorticity. We also find that, for any vorticity, the supercurrent can reverse its flow direction on decreasing the magnetic field before one vortex can escape.