Phase transition and compensation temperature in the mixed spin-1 and spin- anisotropic Heisenberg ferrimagnet

The effects of both an exchange anisotropy and a single-ion anisotropy on the phase diagram and the compensation temperature of the mixed spin-1 and spin- Heisenberg ferrimagnet are investigated by the use of an Oguchi approximation. Particular emphasis is given to the simple cubic lattice with coordination number z=6 for which the phase diagrams are determined numerically and results in some aspects are crucially different from those obtained in the case of the ferromagnet. In particular, the origin and nature of the ordered phases in the ground state are discussed. The existence and dependence of the compensation temperature on a single-ion anisotropy are also investigated.