Neutron Diffraction and Susceptibility Study of Dilute La-Rare-Earth Alloys

Abstract

Neutron diffraction and susceptibility data are reported for dilute solutions of rare-earth impurity in a La host. At magnetic impurity levels of 10 and 20 at.%, the La-Tb alloys show a broad neutron diffraction peak characteristic of short-range order at 7° from the forward direction. At a magnetic impurity level of 5 at.%, this short-range order peak is absent, and the magnetic scattering in the ordered state is the same as the scattering in the paramagnetic state. Within experimental error, the Tb ions maintain their full moment and there is no change in the scattering which can be associated with spin compensation by the conduction electrons. Susceptibility data for these alloys are in many respects similar to results reported for Cu-Mn alloys, but there are important quantitative differences. Pure double-hcp La shows a nearly temperature-independent susceptibility in fair agreement with that predicted from the specific-heat density of states.