Pinning effects in a two-dimensional cluster glass

TL;DR

This study numerically investigates how pinning disorder influences the formation and depinning of two-dimensional cluster glasses formed by vortex-like particles with nonmonotonic interactions, revealing the conditions under which pinning significantly alters glass behavior.

Contribution

It introduces a detailed numerical analysis of pinning effects on cluster glasses with nonmonotonic interactions, highlighting differences from non-cluster systems and the role of pinning density.

Findings

Small pinning densities have limited impact on vortex glass formation.

Higher pinning densities significantly affect glass formation.

Cluster depinning is plastic and involves merging and breaking of clusters.

Abstract

We study numerically the glass formation and depinning transition of a system of two-dimensional cluster-forming monodisperse particles in presence of pinning disorder. The pairwise interaction potential is nonmonotonic, and is motivated by the intervortex forces in type-$1.5$ superconductors. Such systems can form cluster glasses due to the intervortex interactions following a thermal quench, without underlying disorder. We study the effects of vortex pinning in these systems. We find that a small density of pinning centers of moderate depth has limited effect on vortex glass formation, i.e., formation of vortex glasses is dominated by intervortex interactions. At higher densities pinning can significantly affect glass formation. The cluster glass depinning, under a constant driving force, is found to be plastic, with features distinct from non-cluster-forming systems such as clusters merging and breaking. We find that in general vortices with cluster-forming interaction forces can exhibit stronger pinning effects than regular vortices.