Memory and Chaos Effects in Spin Glasses

TL;DR

This study investigates memory and chaos effects in spin glasses through low frequency ac susceptibility measurements, revealing reversible behavior, aging, and memory effects that inform real space models of spin glass dynamics.

Contribution

It provides experimental evidence of chaos and memory effects in spin glasses, highlighting the reversible and aging behaviors during temperature cycling.

Findings

Cooling/heating curves are essentially reversible but rate-dependent.

Aging causes a downward relaxation of susceptibility during stops.

Reheating traces the aging history, demonstrating memory effects.

Abstract

New low frequency ac susceptibility measurements on two different spin glasses show that cooling/heating the sample at a constant rate yields an essentially reversible (but rate dependent) X(T) curve; a downward relaxation of X occurs during a temporary stop at constant temperature (ageing). Two main features of our results are: (i)when cooling is resumed after such a stop, X goes back to the reversible curve (chaos) (ii) upon re-heating, X perfectly traces the previous ageing history (memory). We discuss implications of our results for a real space (as opposed to phase space) picture of spin glasses.