Langevin vortex dynamics for a layered superconductor in the lowest Landau level approximation

TL;DR

This paper numerically investigates vortex dynamics in a layered superconductor using a Ginzburg-Landau model with Langevin dynamics, revealing a first-order vortex lattice freezing transition and its impact on c-axis conductivity.

Contribution

It introduces a Langevin-based numerical approach to study vortex dynamics in layered superconductors within the lowest Landau level approximation, highlighting a first-order freezing transition.

Findings

c-axis conductivity sharply drops at freezing temperature

strong increase in conductivity near melting point

equilibrium properties match previous Monte Carlo results

Abstract

We have numerically investigated the dynamics of vortices in a clean layered superconductor placed in a perpendicular magnetic field. We describe the energetics using a Ginzburg-Landau free energy functional in the lowest Landau level approximation. The dynamics are determined using the time-dependent Ginzburg-Landau approximation, and thermal fluctuations are incorporated via a Langevin term. The c-axis conductivity at nonzero frequencies, as calculated from the Kubo formalism, shows a strong but not divergent increase as the melting temperature $T_M$ is approached from above, followed by an apparently discontinuous drop at the vortex lattice freezing temperature. The discontinuity is consistent with the occurrence of a first-order freezing. The calculated equilibrium properties agree with previous Monte Carlo studies using the same Hamiltonian. We briefly discuss the possibility of detecting this fluctuation conductivity experimentally.