Heterogeneous dynamics of the three dimensional Coulomb glass out of equilibrium

TL;DR

This study investigates the non-equilibrium dynamics of a 3D Coulomb glass, revealing a transition from stationary to non-stationary behavior at the glass transition temperature, with implications for electron diffusion and heterogeneity.

Contribution

It provides new insights into the dynamical heterogeneity and transition behaviors of Coulomb glasses out of equilibrium using kinetic Monte Carlo simulations.

Findings

Transition from stationary to non-stationary dynamics at the glass transition temperature

Identification of two electron groups with different diffusion behaviors

Logarithmic decrease of diffusive electrons during relaxation

Abstract

The non-equilibrium relaxational properties of a three dimensional Coulomb glass model are investigated by kinetic Monte Carlo simulations. Our results suggest a transition from stationary to non-stationary dynamics at the equilibrium glass transition temperature of the system. Below the transition the dynamic correlation functions loose time translation invariance and electron diffusion is anomalous. Two groups of carriers can be identified at each time scale, electrons whose motion is diffusive within a selected time window and electrons that during the same time interval remain confined in small regions in space. During the relaxation that follows a temperature quench an exchange of electrons between these two groups takes place and the non-equilibrium excess of diffusive electrons initially present decreases logarithmically with time as the system relaxes. This bimodal dynamical heterogeneity persists at higher temperatures when time translation invariance is restored and electron diffusion is normal. The occupancy of the two dynamical modes is then stationary and its temperature dependence reflects a crossover between a low-temperature regime with a high concentration of electrons forming fluctuating dipoles and a high-temperature regime in which the concentration of diffusive electrons is high.