Neutron scattering from some light: heavy rare earth alloys

Neutron scattering and susceptibility measurements as a function of temperature are reported on alloys between the light rare earths Pr and Nd and the heavy rare earths Tb, Dy and Ho over the entire composition range. It is clear from the results that the alloys form three distinct crystallographic and magnetic phases dependent upon composition. The heavy rare earth rich alloys remain in the h.c.p. phase like the parent heavy rare earth metal and the magnetic properties are essentially those of a magnetic dilution system. The ordering temperatures are shown to follow a 2/3 power law with reduced deGennes function in common with many other rare earth alloy systems. Alloys containing approximately equal proportions of light and heavy rare earth metals adopt the complicated Sm. structure and, as a result, display a complex magnetic structure. The light rare earth rich alloys display the d.h.c.p. crystallographic structure like Pr and Nd. The magnetic properties of the ferrimagnetic d.h.c.p, alloys are accounted for in terms of a two sublattice model of magnetism.