Crystal fields and exchange in dilute alloys of Tb, Dy, and Er in Y studied for different concentrations

This is a sequel to an earlier paper reporting magnetization measurements on Y-0.14-at.%-Dy and Y-0.14-at.%-Er. In the present paper we have performed similar measurements on different concentrations of dilute Er, Dy, and Tb alloys and also included specific measurements of the basal-plane anisotropy. Crystal-field and exchange parameters were obtained by fits to the inverse initial susceptibility. The anisotropy measurements provide a confirmation of the crystal-field parameters in Dy and Er and are used to deduce $B_{66}$ in Tb. The measurements on different concentrations confirm the adequacy of the theoretical models used. The crystal-field parameters vary substantially with the solute. The molecular-field tensors are highly anisotropic and are approximately independent of concentration at small concentrations.