Temperature dependence of the sound attenuation at the spin glass transition of metallic spin glasses

Abstract

We have measured the sound attenuation (Q −1) in the kHz-range of are-entrant (Metglass 2826A) and a dilute spin glass (Pd(Fe)) with freezing temperatures (T f ) of 1.2 K and 1mK. For the two samplesQ −1 shows a broad maximum atT f. In spite of very differentT f and one order of magnitude difference inQ max − , the reduced curveQ −1 (T)/Q max −1 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.