Transferred hyperfine fields in rare-earth-substituted YFe2 and YNi2

Abstract

In the intermetallic compound YFe2, the metallic hyperfine field at the Y nucleus, as measured by 89Y NMR spectroscopy, is affected by the substitution of one or more neighbour Y atoms by different rare-earth impurities. In order to understand the underlying mechanisms for the transferred hyperfine interaction, we have performed first-principles calculations, within the local spin-density theory, for embedded clusters representing a Y atom and its vicinity in the compounds Y1-xRxFe2 (R=Gd, Tb, Ho, Tm or Lu) and Y1-xGdxNi2. The contact magnetic hyperfine field and the dipolar field were obtained; the resulting total held was found to increase with the spin of the rare-earth impurity. Orbital hyperfine fields were not considered. The contact transferred field was found to arise from direct polarization of the s electrons by the rare-earth spin.