Spin reorientations in La 2− xDy xCo 14B and Y 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 Dy x Co 14B and Y 2− x Tb x Co 14B compounds. Spin orientations in these compounds arise from a competition between the Dy(Tb)-sublattice anisotropy and the Co-sublattice anisotropy. The former dominates at low temperatures, favoring an easy magnetization direction parallel to the c-axis. The latter dominates at high temperatures and favors 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 of the La 2− x Dy x Co 14B system, we observed two spin-reorientation-transition temperatures. This has been explained by the occurrence of regions of slightly different Dy concentration. Magnetic phase diagrams have been presented for the La 2− x Dy x Co 14B and Y 2− x Tb x Co 14B systems.