Memory Effects in the Standard Model for Glasses

TL;DR

This paper investigates memory effects in the standard model of glasses, revealing how disorder influences single-particle and collective memory phenomena, with implications for experimental validation.

Contribution

It demonstrates the conditions under which single-particle memory effects vanish and identifies a collective memory effect analogous to Kovacs' effect in glassy polymers.

Findings

Single-particle memory effects vanish in highly disordered ensembles.

Disordered ensembles exhibit a collective memory effect similar to Kovacs' effect.

Experimental realization can test the model's predictions.

Abstract

The standard model of glasses is an ensemble of two-level systems interacting with a thermal bath. The general origin of memory effects in this model is a quasi-stationary but non-equilibrium state of a single two-level system, which is realized due to a finite-rate cooling and very slow thermally activated relaxation. We show that single particle memory effects, such as negativity of the specific heat under reheating, vanish for a sufficiently disordered ensemble. In contrast, a disordered ensemble displays a collective memory effect [similar to that described by Kovacs for glassy polymers], where non-equilibrium features of the ensemble are monitored via a macroscopic observable. An experimental realization of the effect can be used to further assess the consistency of the model.