Spin reorientations in La 2− xTb xCo 14B compounds

Abstract

We have studied the effect of magnetic dilution on the spin-reorientation transition in the tetragonal La 2− x Tb x Co 14B compounds. Spin reorientations in these compounds arise from a competition between the Tb-sublattice anisotropy and the Co-sublattice anisotropy. The former dominates at low temperatures, favouring an easy magnetization direction parallel to the c-axis. The latter dominates at high temperatures and favours an easy direction perpendicular to the c-axis. As expected, the spin-reorientation-transition temperature decreases with increasing magnetic dilution. In compounds belonging to the middle concentration range, we observed two spin-reorientation-transition temperatures. This has tentatively been explained by the occurrence of an easy-cone structure in a limited temperature range. A magnetic phase diagram has been presented.