Relaxation in yield stress systems through elastically interacting activated events

TL;DR

This paper investigates how long-range elastic interactions influence the dynamics of yield stress materials, revealing a crossover from ballistic to diffusive behavior linked to spatiotemporal correlations.

Contribution

It introduces a two-dimensional mesoscopic model to analyze the effects of elasticity on particle dynamics, extending beyond mean field predictions.

Findings

Ballistic regime shows compressed exponential decay.

Crossover to diffusion linked to spatiotemporal correlations.

Model captures subdiffusive behavior before diffusion onset.

Abstract

We study consequences of long-range elasticity in thermally assisted dynamics of yield stress materials. Within a two-dimensinal mesoscopic model we calculate the mean-square displacement and the dynamical structure factor for tracer particle trajectories. The ballistic regime at short time scales is associated with a compressed exponential decay in the dynamical structure factor, followed by a subdiffusive crossover prior to the onset of diffusion. We relate this crossover to spatiotemporal correlations and thus go beyond established mean field predictions.