Defect-Unbinding Transition in Layered Superconductors

TL;DR

This paper identifies a new defect-unbinding transition in layered superconductors, extending the BKT transition to three dimensions and revealing a topological decoupling transition at finite Josephson coupling.

Contribution

It introduces a novel interstitial-vacancy unbinding transition of BKT type in layered superconductors, linking zero-field superfluidity to finite-field defect dynamics.

Findings

Discovery of a new interstitial-vacancy unbinding transition.

Extension of BKT transition to three-dimensional vortex lattices.

Identification of a topological decoupling transition at finite Josephson coupling.

Abstract

We establish a new interstitial-vacancy unbinding transition of the Berezinskii-Kosterlitz-Thouless type, transforming the three dimensional pancake vortex lattice of a decoupled layered superconductor into a defected solid. This transition is the natural finite-field extension of the vortex-anti-vortex unbinding transition establishing the zero-field superfluid stiffness. At finite Josephson coupling, the defect unbinding transition turns into a topological decoupling transition.