Magnetic relaxation phenomena in a CuMn spin glass

Abstract:

Experiments on the temperature and time dependence of the response function and the field cooled magnetisation of a Cu(Mn) spin glass at temperatures below the zero field spin glass temperature are used to explore the non-equilibrium nature of the underlying spin configuration. The results imply that a certain spin configuration is imprinted on the system as the temperature is decreased at a constant cooling rate. The cooling rate governs the magnitude of the FC magnetisation (M_FC(H,T)). Any intermittent halt at a constant temperature, T_i, imprints an extended spin configuration, a process that is reflected e.g. in a downward relaxation of M_FC. On continued cooling at the same rate, the magnitude of M_FC(T) remains at a lower level than that of a continuous cooling curve. These results are put into the context of the corresponding behaviour of the response function as observed in measurements of the relaxation of the zero field cooled magnetisation.