Distribution of crystal electric fields in amorphous rare-earth alloys

Abstract

We report magnetic measurements on extensive series of amorphous alloys containing small concentrations of rare-earths. We find that the magnetic properties of the rare-earth ions are strongly affected by crystal-field effects, particularly for non-Kramers ion such as Pr ( J = 4), Tb and Tm ( J = 6). Our results cannot be accounted for in models based on simple uniaxial crystal fields. Their analysis in a more general model of quadratic crystal field allows us to derive the distribution of the asymmetry parameter η. Finally we discuss the change of the magnetic behavior and of the local symmetry distribution induced by a structural relaxation of our alloys.