Flux line relaxation kinetics following current quenches in disordered type-II superconductors

TL;DR

This study explores how magnetic vortex lines in disordered type-II superconductors relax after sudden current changes, revealing aging and scaling behaviors through simulations of their dynamics.

Contribution

It introduces a simulation-based analysis of flux line relaxation and aging phenomena following current quenches in disordered superconductors.

Findings

Relaxation dynamics depend on the initial state and quench parameters.

Aging and dynamical scaling emerge after quenches into the pinned state.

Mean velocity and radius of gyration show characteristic relaxation patterns.

Abstract

We investigate the relaxation dynamics of magnetic vortex lines in type-II superconductors following rapid changes of the external driving current by means of an elastic line model simulated with Langevin molecular dynamics. A system of flux vortices in a sample with randomly distributed point-like defects is subjected to an external current of appropriate strength for a sufficient period of time so as to be in a moving non-equilibrium steady state. The current is then instantaneously lowered to a value that pertains to either the moving or pinned regime. The ensuing relaxation of the flux lines is studied via one-time observables such as their mean velocity and radius of gyration. We have in addition measured the two-time flux line height autocorrelation function to investigate dynamical scaling and aging behavior in the system, which in particular emerge after quenches into the glassy pinned state.