The magnetic behaviors of a mixed spin-2 and spin-5/2 Ising ferrimagnetic system on a square lattice are studied with the mean-field approximation (MFA) based on the Bogoliubov inequality for the free energy. A Landau expansion of the free energy in the order parameter is also described in this...

The mixed spin-1 and spin-32 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...

Using an effective-field theory we study a multicritical behaviour of the mixed spin-1 and spin-32 Ising model with different anisotropies on a square lattice. We find a variety of topologies of the finite-temperature phase diagrams, with several multicritical points. The highest-order...

Within an effective-field formalism we study effects of different single-ion anisotropies on the magnetic properties (phase diagram, total and sublattice magnetizations) of a mixed spin-1 and spin-32 Ising ferrimagnetic system on a honeycomb lattice. At a finite temperature we obtain quite a...

The magnetic properties of the mixed spin-12 and spin-1 Ising ferromagnetic system with a crystal–field interaction in the absence and presence of an external magnetic field are studied by using the cluster variation method. Thermal variations of order parameters are investigated and the...

We investigate the critical properties of a mixed spin-1/2 and spin-S(S1/2) transverse Ising model, changing the value of S. In this study, the new type of cluster theory is introduced on the basis of the differential operator technique and Ising spin identities. It is found that the theory...