μSR study of spin fluctuations in RMn4Al8 compounds (R=Tb, Dy, Ho, Er)

The compounds RMn4Al8 are characterized by very weak magnetic interactions between the rare earth (R) sites and the Mn sites. The Mn sites form one-dimensional chains and it likely that this inhibits moment formation and leads to low frequency spin fluctuations. ZF-μSR studies show similar behaviour in all four compounds with R=Tb, Dy, Ho and Er. The relaxation spectrum has two components: the slow relaxation rate peaks below the temperature where the ZFC susceptibility has a cusp, associated with ordering of the Mn moments. The second component has a high relaxation rate that increases rapidly at low temperatures. We tentatively attribute this to the slowing down of the rare earth spin dynamics