Magnetocrystalline Anisotropy in the Systems Samarium-Cobalt-Iron and Samarium-Manganese-Cobalt-Iron.

The anisotropy fields (HA) and saturation magnetizations (4 pi Ms) of the systems Sm2(Co1-xFex)17 and Sm2Mn(Co1-xFex)16 were measured at 4.2 K and 300 K in applied fields up to 100 kOe. The presence of the Mn in the latter system raised the anisotropy fields by as much as 55% over those measured for the corresponding compounds in the ternary system. The augmentation of anisotropy was accompanied by a slight decline in 4 pi Ms of approximately 5% for the materials of highest HA. The values of 4 pi Ms for the quaternary compounds showed much less temperature dependence, increasing by about 5% in going from 300 K to 4.2 K as compared to 15% for the ternary system. A comparison of the present HA results with previous anisotropy measurements of Perkins and Straessler, obtained by extrapolation from applied fields up to 20 kOe showed the latter to be too low by as much as 50%. The effect of the higher HA values on the anisotropy constant Kl and the crystal field parameter r ang 2 will be presented and the consequences discussed. (Author)