Intermittency, aging and record fluctuations

Original · EN

Aging in spin glasses is analyzed via the Probability Density Function (PDF) of the heat transfer between system and bath over a small time δt. The PDF contains a Gaussian part, describing reversible fluctuations, and an exponential tail caused by intermittent events. We find that the relative weight of these two parts depends, for fixed δt, on the ratio of the total sampling time to the age tw. Fixing this ratio, the intensity of the intermittent events is proportional to δt/tw and independent of the temperature. The Gaussian part has a variance with the same temperature dependence as the variance of the equilibrium energy in a system with an exponential density of states. All these observations are explained assuming that, for any tw, intermittent events are triggered by local energy fluctuations exceeding those previously occurred.