Relaxation dynamics in type-II superconductors with point-like and correlated disorder

TL;DR

This study uses Langevin molecular dynamics to analyze the relaxation and steady-state behavior of magnetic vortices in disordered type-II superconductors, comparing point-like and correlated disorder effects.

Contribution

It introduces a detailed LMD approach to distinguish relaxation features under different disorder types and validates findings against Monte Carlo simulations.

Findings

LMD results agree with Monte Carlo data

Distinct relaxation behaviors for point-like vs. correlated disorder

Quantitative dependence of vortex dynamics on driving current

Abstract

We employ an elastic line model to investigate the steady-state properties and non-equilibrium relaxation kinetics of magnetic vortex lines in disordered type-II superconductors using Langevin molecular dynamics (LMD). We extract the dependence of the mean vortex line velocity and gyration radius as well as the mean-square displacement in the steady state on the driving current, and measure the vortex density and height autocorrelations in the aging regime. We study samples with either randomly distributed point-like or columnar attractive pinning centers, which allows us to distinguish the complex relaxation features of interacting flux lines subject to extended vs. uncorrelated disorder. Additionally, we find that our new LMD findings match earlier Monte Carlo (MC) simulation data well, verifying that these two microscopically quite distinct simulation methods lead to macroscopically very similar results for non-equilibrium vortex matter.