Kovacs-like memory effect in a sheared colloidal glass: role of non-affine flows

TL;DR

This study demonstrates Kovacs-like memory effects in sheared colloidal glasses through experiments, simulations, and theory, emphasizing the role of non-affine flows and nonlinear perturbations in out-of-equilibrium systems.

Contribution

It extends the understanding of Kovacs-like memory effects to volume-conserving shear perturbations and highlights the influence of microscopic non-affine flows on memory behavior.

Findings

Kovacs-like memory effect observed under shear in colloidal glasses.

Non-linear perturbations increase deviation from linear response predictions.

Microscopic non-affine flows significantly influence the memory effect.

Abstract

Memory effect reflects a system's ability to encode, retain and retrieve information about its past. Such effects are essentially an out-of-equilibrium phenomenon providing insight into the complex structural and dynamical behavior of the system. Kovacs effect is one such memory effect that is traditionally associated with thermal history. Although studies on the Kovacs-like memory effect have been extended to mechanical perturbations such as compression-decompression, whether such effects can also be observed under volume-conserving perturbations like shear, remains unclear. Combining experiments, simulations and linear response theory we demonstrate Kovacs-like memory effect in a sheared colloidal glass. Moreover, we explore the influence of non-linear perturbations and establish a correlation between the deviation from linear response prediction and microscopic non-affine flows generated due to such large deformations in affecting the memory effect. Our study not only extends Kovacs-like memory effect in the domain of volume-conserving mechanical perturbations, it also highlights the importance of the nature of underlying microscopic flows in controlling the memory effect in amorphous matter.