Mean-field solution of the mixed spin-1 and spin- Ising system with different single-ion anisotropies

The mixed spin-1 and spin- Ising ferrimagnetic system with different anisotropies is studied within the mean-field theory based on Bogoliubov inequality for the Gibbs free energy. Global phase diagrams are obtained in the temperature-anisotropy plane. In particular we find first-order transition lines separating different low-temperature ordered phases (characterized by different values of the sublattice magnetizations) each one terminating at an isolated critical point. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.