MOSSBAUER STUDY INDICATING MAGNETIC CLUSTERS IN FENIMN-REENTRANT SPIN-GLASS ALLOYS

Fe-57 Mossbauer measurements on the reentrant spin glass system (Fe.65Ni.35)1-x Mn(x) are analysed under the extreme assumption that only relaxation determines the shape of the spectra. A plain model of a fluctuating hyperfine field based on the Blume-Tjon-theory /1/ is used for the evaluation. As a result the increase of the fluctuation frequencies with increasing temperature yields in lowering of the relative magnetization. Noticeable are some typical kinks of the magnetization at the reentrant temperatures. Our evaluation results in fluctuation frequencies from 10(7) Hz to 10(9) Hz, which indicates, if true, that the reason of the fluctuations seems not to be single spins but larger collective spin groups (clusters).