Limited quenching of the holmium moment by the crystal field in the (Gd,Y)Ni2cubic Laves phase compounds

Abstract

The hyperfine interaction of $^{165}\mathrm{Ho}$ in the cubic Laves phase compounds ${\mathrm{Ho}}_{0.01}{\mathrm{Gd}}_{1\ensuremath{-}x}{\mathrm{Y}}_{x}{\mathrm{Ni}}_{2}$ has been investigated by spin-echo NMR in the composition range $0<x<0.18$. In the end compound ($x=0$) a value of ${9.5}_{\mathrm{\ensuremath{\mu}}\mathit{B}}$ is obtained for the holmium moment which indicates a 5% quenching by the crystalline electric field. Further quenching takes place with substitution of yttrium for gadolinium. The magnetization anisotropy of these compounds is weak. The substitution of 1-at.% Ho for Gd suffices to rotate the easy axis of magnetization in Gd${\mathrm{Ni}}_{2}$ from the $〈110〉$ to the $〈100〉$ direction. This direction remains the easy magnetization direction in all compounds studied. The transferred hyperfine interaction is long range and analysis of data indicates considerable participation of the $d$ electrons in the hyperfine interaction in this series.