Coarsening of Topological Defects in Oscillating Systems with Quenched Disorder

TL;DR

This study uses large-scale simulations to explore how topological defects in two-dimensional driven disordered systems evolve over time, revealing different decay behaviors depending on quench depth and drive amplitude.

Contribution

It demonstrates the coarsening dynamics of topological defects during dynamical reordering in driven disordered systems, including power-law and logarithmic decay regimes.

Findings

Defect density decays as a power law near the disorder-order crossover.

Deep quenches lead to a logarithmic decay of defect density.

Similar decay behaviors are observed even without pinning.

Abstract

We use large scale simulations to study interacting particles in two dimensions in the presence of both an ac drive and quenched disorder. As a function of ac amplitude, there is a crossover from a low drive regime where the colloid positions are highly disordered to a higher ac drive regime where the system dynamically reorders. We examine the coarsening of topological defects formed when the system is quenched from a disordered low ac amplitude state to a high ac amplitude state. When the quench is performed close to the disorder-order crossover, the defect density decays with time as a power law with \alpha = 1/4 to 1/3. For deep quenches, in which the ac drive is increased to high values such that the dynamical shaking temperature is strongly reduced, we observe a logarithmic decay of the defect density into a grain boundary dominated state. We find a similar logarithmic decay of defect density in systems containing no pinning. We specifically demonstrate these effects for vortices in thin film superconductors, and discuss implications for dynamical reordering transition studies in these systems.