Czechoslovak Journal of Physics 46, 2227 (1996)

Ermile Gaganidze and Pablo Esquinazi

Abstract

We have measured the sound attenuation (Q^-1) in the kHz-range of a re-entrant (Metglass 2826A) and a dilute spin glass (Pd(Fe)) with freezing temperatures ( T_f ) of 1.2 K and 1 mK. For the two samples Q^-1 shows a broad maximum at T_f. In spite of very different T_f and one order of magnitude difference in Q_max^-1, the reduced curve Q^-1(T) / Q_max^-l vs. T / T_f follows the same temperature dependence. We show that this dependence can be well described with a thermally activated phonon-spin relaxation time with a broad distribution of activation energies. The maximum activation energy of the distribution scales with the freezing temperature.