Origins of magnetic anisotropy in cubic RFe2 Laves phase compounds

Detailed studies of magnetic anisotropy and spin orientations in ternary and quaternary high magnetostriction compounds of the form HoxTbyDy1−x−yFe2 have clearly demonstrated the existence of both continuous and discontinuous rotation of the easy axis between principal crystallographic directions as a function of composition and temperature. While the usual single ion crystal field model successfully explains the qualitative features of the data, there still remain significant differences between the actual and predicted compositions at which the rotations occur. We show that these differences are largely due to changes in the magnetoelastic energy with spin orientation.