Neutron depolarization due to ferromagnetism and spin freezing in CePd_{1−x}Rh_{x}

Abstract

We report neutron depolarization measurements of the suppression of long-range ferromagnetism and the concomitant emergence of magnetic irreversibilities and spin freezing in CePd_{1−x}Rh_{x} around x^{*}≈0.6. Tracking the temperature versus field history of the neutron depolarization, we find clear signatures of long-range Ising ferromagnetism below a Curie temperature T_{C} for x=0.4 and a spin freezing of ferromagnetic clusters below a freezing temperature T_{F1} for x>x^{*}. Under zero-field-cooling/field-heating and for x>x^{*} a reentrant temperature dependence of the neutron depolarization between T_{F2}<T_{F1} and T_{F1} is microscopically consistent with a thermally activated growth of the cluster size. The evolution of the depolarization as well as the reentrant temperature dependence as a function of Rh content are consistent with the formation of a Kondo cluster glass below T_{F1} adjacent to a ferromagnetic quantum phase transition at x^{*}.