Two-step melting of the vortex solid in layered superconductors with random columnar pins

TL;DR

This study reveals that in layered superconductors with random columnar pins, vortex solid melting occurs in two steps involving a Bragg glass, an intermediate Bose glass, and a vortex liquid, with spatially varying melting temperatures.

Contribution

It introduces a detailed numerical analysis showing two-step melting in vortex solids with random columnar pins, highlighting the intermediate Bose glass phase.

Findings

Melting occurs in two steps: Bragg glass to Bose glass, then Bose glass to vortex liquid.

Spatial variation in local melting temperature matches experimental observations.

Identification of an intermediate Bose glass phase during melting process.

Abstract

We consider the melting of the vortex solid in highly anisotropic layered superconductors with a small concentration of random columnar pinning centers. Using large-scale numerical minimization of a free-energy functional, we find that melting of the low-temperature, nearly crystalline vortex solid (Bragg glass) into a vortex liquid occurs in two steps as the temperature increases: the Bragg glass and liquid phases are separated by an intermediate Bose glass phase. A suitably defined local melting temperature exhibits spatial variation similar to that observed in experiments.