Transition to a Superconductor with Insulating Cavities

TL;DR

This paper investigates how internal insulating cavities in an extreme type II superconductor can lower its energy compared to a defect-free superconductor above a certain magnetic field, using numerical Ginzburg-Landau simulations.

Contribution

It demonstrates that insulating cavities can stabilize superconductors at high magnetic fields, a novel insight into defect engineering in superconducting materials.

Findings

Insulating cavities reduce superconductor energy above a critical magnetic induction.

Metallic cavities do not lower energy compared to defect-free superconductors.

Numerical simulations compare free energy densities for various cavity sizes and densities.

Abstract

An extreme type II superconductor with internal insulating regions, namely cavities, is studied here. We find that the cavity-bearing superconductor has lower energy than the defect-free superconductor above a critical magnetic induction $B^*$ for insulating cavities but not for metallic ones. Using a numerical approach for the Ginzburg-Landau theory we compute and compare free energy densities for several cavity radii and at least for two cavity densities, assuming a cubic lattice of spherical cavities.