Muon Spin Relaxation Study of Reentrant Spin Glasses: Amorphous-Fe_{1-x}Mn_x

We have performed an extensive muon spin relaxation study of the well known (Fe$_{1-x}$Mn$_{x}$)$_{75}$P$_{16}$B$_6$Al$_3$ reentrant spin glass. We find a strong increase of the dynamic as well as static muon depolarization rate at the paramagnetic to ferromagnetic transition temperature, $T_c$, and at $T_f$ ($T_f<T_c$) that corresponds to the onset of strong bulk magnetic irreversabilities. We find no critical dynamic signature of a freezing of the transverse $XY$ spin components at an intermediate temperature $T_{xy}$ ($T_f < T_{xy} < T_c$) where extra static order not contributing to the magnetization starts developping.