Probing exotic spin correlations by muon spin depolarization measurements with applications to spin glass dynamics

Abstract

We develop a new method to probe the local spin dynamic autocorrelation function, using magnetic field dependent muon depolarization measurements. We apply this method to muSR experiments in the dilute Heisenberg spin glass AgMn(p at. %) at T>T_g where the correlations of the Mn local magnetic moment are strongly non-exponential. Our results clearly indicate that the dynamics of this spin glass cannot be described by a distribution of correlation times. Therefore, we analyze the data assuming a local spin correlation function which is the product of a power law times a cutoff function. The concentration and temperature dependence of the parameters of this function are determined. Our major conclusion is that in the temperature region close to Tg the correlation function is dominated by an algebraic relaxation term.