Conduction Electron Polarization in Mixed Scandium Laves Phases with Cobalt and Nickel

Abstract

The Knight shift K and linewidth δH of the ⁴⁵Sc NMR in the cubic Laves phase intermetallic system Sc(Co_xNi_1−x)₂, where 0≤x≤1, have been investigated at 300°K. In accord with the probable simple Pauli paramagnetism of ScNi₂, K=+0.39%, whereas in ScCo₂, K=−0.43%, indicative of a d‐spin contribution to K from the Co° (d⁹) ions. In ScCo₂, δH may be interpreted as resulting from the exchange‐narrowed dipolar field of the Co ions, with J/k=0.44°K. In the mixed compounds, δH varies linearly both with applied field H and composition x above and below x=0.5, and the average K varies smoothly, but not linearly, between the ScNi₂ and ScCo₂ values. The field and composition dependence of δH may be interpreted in terms of a distribution of K values resulting from the random distribution of Co neighbors. Preliminary measurements of the volume susceptibility indicate that the Knight shift and susceptibility may be directly correlated.