No abstract

No abstract

In this paper we study the critical behaviors of the half-integer mixed spin-3/2 and spin-5/2 Blume -Capel Ising ferrimagnetic system by using the exact recursion relations on the Bethe lattice for 4 q = and 6, whose real lattice correspondences are square and simple cubic lattices, respectively. We have obtained the phase diagrams in the , the reduced crystal field of the sublattice with spin-3/2. Even if the system presents both second-and first-order phase transitions, their lines never connect to each other and end at critical points; thus, no tricritical points are observed. We have also found the existence of one or two compensation temperatures for appropriate values of the crystal fields, therefore observing reentrant behavior for some of the compensation lines.

No abstract

The phase diagrams of spin-1/2 Ising model on a two-layer Bethe lattice with antiferromagnetic interactions for each layer and either antiferromagnetic or ferromagnetic interaction between the layers are investigated by using the pairwise approach for given values of coordination number q. The exact expressions of the order--parameters, response functions and free energy are obtained in terms of the recursion relations. The ground-state phase diagrams are calculated for given system parameters of the model. In the guidance of the ground-state phase diagrams, the temperature dependent phase diagrams of the model are also studied in detail for given coordination numbers q = 3, 4 and 6. It was found that the system presents only second-order phase transitions with different thermal behaviors for all values of q. In addition, two Néel temperatures, T N , are found for q = 6 only.