Depinning and dynamics of AC driven vortex lattices in random media

TL;DR

This paper investigates the complex dynamics of vortex lattices under AC forces in disordered media, highlighting the importance of quadratic displacement over mean velocity for identifying depinning and revealing hysteretic effects.

Contribution

It introduces a novel approach using mean quadratic displacement to characterize AC-driven vortex depinning, uncovering hysteresis absent in DC systems.

Findings

Quadratic displacement is a better indicator of depinning than mean velocity.

Hysteretic effects are observed in AC-driven vortex lattices.

Results depend on initial configurations and frequency of applied forces.

Abstract

We study the different dynamical regimes of a vortex lattice driven by AC forces in the presence of random pinning via numerical simulations. The behaviour of the different observables is charaterized as a function of the applied force amplitude for different frequencies. We discuss the inconveniences of using the mean velocity to identify the depinnig transition and we show that instead, the mean quadratic displacement of the lattice is the relevant magnitude to characterize different AC regimes. We discuss how the results depend on the initial configuration and we identify new hysteretic effects which are absent in the DC driven systems.