Crystal field effects in amorphous rare earth magnetic materials

A model proposed by Harris et al. in which crystal field affects are important, is extended to consider the magnetic properties of amorphous materials containing localized ionic moments of a single, heavy rare earth, magnetic element. The paramagnetic and ferromagnetic properties are investigated for all the heavy rare earths. It is found that the average spontaneous moment per ion in the amorphous state can be lowered below the free ion moment by more than 50%, but the relative reduction in Curie temperature is much less marked than found by Harris et al.