Memory in an aging molecular glass

TL;DR

This study investigates the memory effects in the dielectric susceptibility of aging molecular glass sorbitol, revealing how the out-of-equilibrium state evolves during temperature cycling and differs from spin glass behavior.

Contribution

It provides new insights into the aging and memory phenomena in molecular glasses, highlighting differences from spin glasses and linking behavior to the energy landscape.

Findings

Memory effects are observed during temperature cycling.

Effective aging depends on temperature relative to the stop.

Differences from spin glass memory are discussed.

Abstract

The dielectric susceptibility of the molecular liquid sorbitol below its calorimetric glass transition displays memory strikingly similar to that of a variety of glassy materials. During a temporary stop in cooling, the susceptibility changes with time, and upon reheating the susceptibility retraces these changes. To investigate the out-of-equilibrium state of the liquid as it displays this memory, the heating stage of this cycle is interrupted and the subsequent aging characterized. At temperatures above that of the original cooling stop, the liquid enters a state on heating with an effective age that is proportional to the duration of the stop, while at lower temperatures no effective age can be assigned and subtler behavior emerges. These results, which reveal differences with memory displayed by spin glasses, are discussed in the context of the liquid's energy landscape.