Comparison of spin-glass dynamics determined by the muon-spin-relaxation and neutron spin-echo techniques

Impurity-spin-correlation functions obtained from muon-spin-relaxation and neutron spin-echo experiments are found to agree quantitatively above and below the "glass" temperature $T_g$. The agreement confirms the power-law decay of correlations in time near and below $T_g$. Features of the experimental results which depend on (quasi)static impurity-spin correlations suggest that the spatial distribution of thermally averaged impurity-spin magnitudes is quite uniform below $T_g$. The stochastic behavior of dipolar fields at muon sites is essentially the same as that of the impurity spins themselves at all temperatures.