Depinning and critical current characteristics of topologically defected vortex lattices

TL;DR

This paper investigates how dislocation structures like grain boundaries influence the depinning and critical current in vortex lattices, revealing their key role in the flow response and transport properties of superconductors.

Contribution

It provides a simulation-based analysis of vortex polycrystals, confirming analytical predictions and highlighting the importance of topological defects in vortex lattice dynamics.

Findings

Critical current increases with pinning density.

Crossover in depinning behavior observed.

Results align with grain boundary depinning theory.

Abstract

We discuss the role of dislocation assemblies such as grain boundaries in the dynamic response of a driven vortex lattice. We simulate the depinning of a field-cooled vortex polycrystal and observe a general enhancement of the critical current as well as a distinct crossover in the characterisitic of this quantity as a function of pinning density. The results agree with analytical predictions for grain boundary depinning. The dynamics of grain boundaries thus proves an essential mechanism underlying the flow response of defected vortex lattices and the corresponding transport properties of the superconducting material. We emphasize the connection between the topological rearrangements of the lattice and its threshold dynamics. Our theory encompasses a variety of experimental observations in vortex matter as well as in colloidal crystals.