Nuclear orientation studies of magnetism in rare earth intermetallic alloys

Full text: Studies of bulk magnetism in rare earth (RE) compounds are common place. However little work has been done with RE ions as dilute impurities in RE compounds simply because it is difficult, with many techniques, to distinguish the impurity signature from the bulk magnetism. Low temperature nuclear orientation (LTNO) employing radioactive tracers is one technique that does allow such measurements to be made routinely. Furthermore, LTNO also can be used to distinguish between the magnetic contributions of various bulk RE ions in ternary etc. compounds. The ability of LTNO to isolate the magnetic anisotropies of dilute impurity and host RE ions within a single material has been recently illustrated by work on single crystal Pr0.5Nd0.5Ni. In this instance LTNO of radioactive 142Pr and 147Nd probes formed by neutron radiation and representative of the bulk ions show unique and different axes of easy magnetisation for the two RE species; dilute impurity 143,144Pm ions formed by alpha irradiation of the same host are found to align close to the Nd direction. In this paper we present further measurements on the Pr0.5Nd0.5Ni system as well as related RENi compounds utilising probes isoelectronic to the bulk RE as well as Pm impurities and compare these results with earlier work. Preliminary measurements on several antiferromagnetic RENiAl4 compounds are also presented in the context of illustrating the capabilities of the LTNO technique in this field