Sliding states of a soft-colloid cluster crystal: Cluster versus single-particle hopping

TL;DR

This paper investigates the depinning and sliding behavior of a 2D colloidal cluster crystal under external force, revealing complex dynamics including cluster and single-particle hopping, and the effects of temperature on mobility.

Contribution

It introduces a detailed analysis of the competition between cluster and single-particle sliding in a soft-colloid model with periodic pinning, highlighting new dynamical regimes.

Findings

Identification of cluster versus single-particle hopping regimes

Dependence of sliding behavior on particle density and potential amplitude

Finite temperature smooths the mobility-force relationship

Abstract

We study a two-dimensional model for interacting colloidal particles which displays spontaneous clustering. Within this model we investigate the competition between the pinning to a periodic corrugation potential, and a sideways constant pulling force which would promote a sliding state. For a few sample particle densities and amplitudes of the periodic corrugation potential we investigate the depinning from the statically pinned to the dynamically sliding regime. This sliding state exhibits the competition between a dynamics where entire clusters are pulled from a minimum to the next and a dynamics where single colloids or smaller groups leave a cluster and move across the corrugation energy barrier to join the next cluster downstream in the force direction. Both kinds of sliding states can occur either coherently across the entire sample, or asynchronously: the two regimes result in different average mobilities. Finite temperature tends to destroy separate sliding regimes, generating a smoother dependence of the mobility on the driving force.