Time dependent critical field transition line in an insulating spin-glass

Abstract

The change in magnetization of the insulating spin-glass Eu0.4Sr0.6S has been measured as a function of time (1 ms-1 s) for small magnetic field changes superposed on a larger constant field. A set of field-temperature transition lines has been obtained for different time scales. Each appears to be of the De Almeida-Thouless form but with a field scale which is dependent (independent) of the time scale for times > () 10 ms. The results are analysed in terms of recent theories.