Critical Behaviour of the Ferromagnetic Spin-3/2 – Blume-Emery-Griffiths Model with Repulsive Biquadratic Coupling

Abstract

The critical behaviour of the ferromagnetic spin-3 2 Blume-Emery-Griffiths model with repulsive biquadratic coupling in the absence and presence of an external magnetic field is studied by using the lowest approximation of the cluster variation method, which is identical with the mean-field approximation. Thermal variations of the order parameters are investigated for different values of the interaction parameters and the external magnetic field. The complete phase diagrams of the system are calculated in the (kT /J, K/J), (kT /J, D/J) and (kT /J, H/J) planes. Five new phase diagram topologies are obtained, which are either absent from previous approaches or have gone unnoticed. A detailed discussion and comparison of the phase diagrams is made.

The Study of the Three-dimensional Spin-3/2 Ising Model on a Cellular Automaton

“…All these studies were done by different methods, such as mean field approximation (MFA) [1][2][3][4], renormalization group (RG) methods [5,6], the effective-field theory (EFT) [7][8][9], cluster variation method (CVM) [10][11][12] and Monte Carlo (MC) simulation [3,13]. Most of these studies have considered some portion of the phase diagram of the model.…”

“…These models were also studied by using the EFT [8] and CVM [10]. Recently, the phase diagrams of the spin-3/2 BEG model in the (D/J, kT/J) plane for several values of K/J and in the (K/J, kT/J) plane for several values of D/J have been presented [6,11,12]. In spite of these studies, further studies using alternative methods are desirable to obtain the new phase diagrams and the critical behavior of the model.…”