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

We develop a method to probe the local spin dynamic autocorrelation function, using magnetic-field-dependent muon depolarization measurements. We apply this method to muon spin relaxation experiments in the dilute Heisenberg spin glass AgMn $(p$ at. %) at T>Tg, where the correlations of the Mn local magnetic moment are strongly nonexponential. 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.