Crystal-Field Effects in Solid Solutions of Rare Earths in Noble Metals

The magnetic susceptibility of some dilute alloys has been measured between 1.9 and 300°K by a force method. The investigation has been concerned mainly with solid solutions of 1 at.% or less of the elements of the second half of the rare-earth series in silver or gold, in order to study local moments of the impurity ions. The observed departures of the susceptibility from a Curie-Weiss behavior can be understood and fitted primarily in terms of crystal-field effects; the possible origins of such fields are discussed. It is found that the fitted crystalline fields are incompatible with a point-charge model, but can be explained by the hypothesis of a nonmagnetic $5d$ virtual bound state on the rare-earth impurity.