MAGNETIC-PROPERTIES OF METASTABLE HCP SAMARIUM

Melt-quenched h.c.p. Sm has a magnetic ordering temperature of 165 K, which is anomalously high for a light rare earth metal. Below that temperature, a field cooling effect is observed in the thermomagnetic curve, indicating that this phase has a very large coercive field. For the sample cooled in a field of 17.3 kOe, the magnetization in the ordered state is only about 2 e.m.u. g-1, and a broad maximum in the magnetization is observed around 130 K. The paramagnetic susceptibility of this phase is larger than that of the normal rhombohedral Sm and decreases monotonically with increasing temperature. Two small steps of irreversible decrease are observed around 400 K and 600 K for as-quenched sample. Compared with the results of an X-ray diffraction study, the latter anomaly corresponds to the transition from the h.c.p. phase to the rhombohedral phase, although the former is uncertain.