# Self-diffusion in plastic flow of amorphous solids

## TL;DR

This study uses particle-based simulations to explore how avalanche-like plastic events influence self-diffusion in sheared amorphous solids, revealing size-dependent diffusion behavior linked to collective slip patterns.

## Contribution

It demonstrates the impact of avalanche dynamics on particle self-diffusion and highlights size effects in the diffusion coefficient in dense amorphous solids under shear.

## Key findings

- Avalanche dynamics significantly influence tracer particle diffusion.
- Size effects are prominent in the effective diffusion coefficient.
- Plastic event distributions relate to diffusion behavior.

## Abstract

We report on a particle-based numerical study of sheared amorphous solids in the dense slow flow regime. In this framework, deformation and flow are accompanied by critical fluctuation patterns associated with the macroscopic plastic response and single particle kinematics. The former is commonly attributed to the collective slip patterns that relax internal stresses within the bulk material and give rise to an effective mechanical noise governing the latter particle-level process. In this work, the avalanche-type dynamics between plastic events is shown to have a strong relevance on the self-diffusion of tracer particles in the Fickian regime. As a consequence, strong size effects emerge in the effective diffusion coefficient that is rationalized in terms of avalanche size distributions and the relevant temporal occurrence.