Evidence for power-law spin-correlation decay from muon spin relaxation in AgMn spin-glass

Muon spin relaxation measurements have been carried out below the "glass" temperature Tg in AgMn spin-glasses. The muon spin-lattice relaxation rate varies with field H as H-0.46±0.05 for 0.30<~T/Tg<~0.66. This suggests that impurity-spin correlations decay with time as t-ν, ν≈0.54±0.05, in contrast to the more usual exponential decay. The present data therefore agree quantitatively with the prediction ν≈½ of mean-field dynamic theories