New Model for Amorphous Magnetism

We propose a new model for magnetism in an amorphous material. The model is particularly appropriate for rare-earth compounds such as Tb${\mathrm{F}}_2$. It is a Heisenberg model in which each ionic spin is subjected to a local anisotropy field of random orientation. We discuss the magnetic properties of two simple ionic configurations, and show that the model is in qualitative agreement with the experimental data.