Memory and Rejuvenation in Glassy Systems

TL;DR

This paper investigates the memory effect in a spin glass through ac susceptibility measurements and develops a model explaining how correlated regions grow and influence memory loss during temperature changes.

Contribution

It introduces a model based on correlated region growth that quantitatively explains the memory effect in spin glasses across different temperatures.

Findings

Memory effect depends on growth of correlated regions

Model accurately predicts memory magnitude based on waiting times

Memory loss relates to relative change in correlated volume

Abstract

The memory effect in a single crystal spin glass ($\mathrm{Cu}_{0.92}\mathrm{Mn}_{0.08}$) has been measured using \freq ac susceptibility techniques over a temperature range of $0.4 - 0.7 \, T_g$ and a model of the memory effect has been developed. A double-waiting-time protocol is carried out where the spin glass is first allowed to age at a temperature below $T_g$, followed by a second aging at a lower temperature, \Tw{2}, after it has fully rejuvenated. The model is based on calculating typical coincident growth of correlated regions at the two temperatures. It accounts for the absolute magnitude of the memory effect as a function of both waiting times and temperatures. The data can be explained by the memory loss being a function of the relative change in the correlated volume at the first waiting temperature because of the growth in the correlations at the second waiting temperature.