Obtaining the phase diagrams of mixed spin-3/2 and spin-5/2blume-emery-griffiths model on bethe lattice

This thesis is a comprehensive study of the critical behavior of the mixed spin-3/2 and spin-5/2 Blume-Emery-Griffiths (BEG) model on the Bethe Lattice. The model was theoretically investigated on the Bethe Lattice using the exact recursion relations method. The expressions of the sublattice magnetizations and quadrupole moments of the model were obtained in terms of the exact recursion relations. These equations were solved using the numerical iteration method in a suitable computer programming language. Thermal changes of these order parameters in the absence and presence of the crystal field interaction parameter were investigated. This study includes a detailed analysis of the phase transitions occurring in the system, whether they are first-order, second-order or higher-order. Phase diagrams of the mixed spin-3/2 and spin-5/2 isotropic BEG model in the absence of the crystal field parameter in the (K, T) plane for coordination numbers q=3 and 4, and phase diagrams of the mixed spin-3/2 and spin-5/2 BEG model for various negative biquadratic interaction parameters in the presence of the crystal field parameter in the (D, T) plane for coordination numbers q=3 and 4 are obtained in detail. Second-order and first-order phase transition lines were found in the model. Isolated critical end points where first-order phase transition lines end were detected. No compensation temperature point was detected in either case