Magnetic Studies of Some Intermetallic Compounds between Cobalt and the Lanthanide Elements

Abstract

Thermomagnetic studies of intermetallic compounds having the stoichiometry ACo₅, in which A represents yttrium or a lanthanide element, have been extended to liquid helium temperatures. At applied magnetic fields of 2600 and 7200 oe, anomalies not appearing at high fields have been observed in the behavior of PrCo₅ and NdCo₅. These anomalies are an apparent second (low‐temperature) Curie point at about 126°K in PrCo₅ and a maximum in the thermomagnetic curve of NdCo₅ in the vicinity of 270°K. The data obtained for other ACo₅ compounds are consistent with those reported recently by Nesbitt et al. Results for PrCo₅ and NdCo₅ indicate ferromagnetic coupling of the cobalt moments on cooling below 910° and 925°K, respectively, while in each case at low fields, the lanthanide moments remain disordered. With PrCo₅ the data indicate ferromagnetic coupling of the Pr and Co moments below 126°K. Data for NdCo₅ suggest that on cooling, a similar type of coupling develops at about 270°K, but this is almost immediately superseded by antiferromagnetic coupling of the Nd moments with one another at lower temperatures.