Stabilization of vortex-antivortex configurations in mesoscopic superconductors by engineered pinning

TL;DR

This paper demonstrates how engineered nanoholes in mesoscopic superconductors can stabilize vortex-antivortex configurations, making them more experimentally accessible and revealing new asymmetric ground states influenced by screening effects.

Contribution

The study introduces a method of using nanoholes to stabilize vortex-antivortex states and explores the impact of screening and geometry on these configurations.

Findings

Nanoholes significantly enhance vortex-antivortex stability.

Perforated disks favor giant-antivortex states.

Screening effects destabilize vortex-antivortex configurations.

Abstract

Symmetry-induced vortex-antivortex configurations in superconducting squares and triangles were predicted earlier; yet, they have not been resolved in experiment up to date. Namely, with vortex-antivortex states being highly unstable with respect to defects and temperature fluctuations, it is very unlikely that samples can be fabricated with the needed quality. Here we show how these drawbacks can be overcome by strategically placed nanoholes in the sample. As a result, (i) the actual shape of the sample becomes far less important, (ii) the stability of the vortex-antivortex configurations in general is substantially enhanced, and (iii) states comprising novel giant-antivortices (with higher winding numbers) become energetically favorable in perforated disks. In the analysis, we stress the potent of strong screening to destabilize the vortex-antivortex states. In turn, the screening-symmetry competition favors stabilization of new asymmetric ground states, which arise for small values of the effective Ginzburg-Landau parameter kappa.