Spin-reorientation transitions and magnetic anisotropy in TbFe11-xCoxTi compounds

The aim of this work is to study the influence of substitution of Co for Fe on the magnetocrystalline anisotropy and spin reorientation transition in TbFe11-xCoxTi (x=0;0.5;1;2;3;4;5) compounds. The anisotropy study has been performed by means of torque and magnetization measurements on single crystal samples. It was shown that increase of the Co content in Tb(FeCo)11Ti compounds leads to an increase of the Curie temperatures Tc. The temperature of the magnetic phase transition during which the easy magnetic direction (EMD) changes from the c-axis via a cone to the basal plane has been found to decrease with increasing Co concentration. On the basis of the experimental results a T-x magnetic phase diagram was constructed. The appearance of phase transitions can be explained by the temperature-dependent competition between the planar Tb sublattice anisotropy and the transition metal (FeCo)11 sublattice anisotropy. (orig.)