Anisotropy in RFe2 Intermetallics: An NMR Study

The anisotropy of the Ho^3+, Tb^3+ and Tm^3+ rare-earth ions in RFe2 compounds is investigated using the field dependence of the NMR spectra of 169Tm, 159Tb and 165Ho in polycrystalline TmFe2, TbFe2, HoFe2 and related pseudo-binary compounds. The very large hyperfine interaction in these ions dominates the NMR spectrum; the NMR frequencies in the 2 to 7 GHz range provide therefore a measure of the localized 4 f moment and its orientation in the crystal field. We compare the NMR measurements to single ion computations that include magnetostriction.