The spin‐3/2 Blume–Emery–Griffiths model with repulsive biquadratic coupling in an external field

Abstract

The spin-3/2 Blume-Emery-Griffiths model is solved on the Bethe lattice in the absence and presence of the external field using the iteration technique (recursion method). The phase diagrams are obtained for the coordination number q = 3, 4, 6 and 8. We confirm the existence of a staggered quadrupolar phase in addition to a ferrimagnetic and ferromagnetic ordered phases and analyze the occurence of re-entrant boundaries inside the ordered region as a character of the coordination of the lattice. A comparison is made with the results of other approximate methods.

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

“…Figure 6 Figure 6. This phase diagram also agrees very well with the recent work for q > 6 [13]. Moreover, these three phase diagrams exhibit a reentrant behaviour.…”

“…5a and b, in which one of them, Fig. 5a shows a similar phase diagram topology as recently obtained by Ekiz [13] for q > 6, q is the coordination number. The other phase diagram, Fig.…”

“…One should also notice a pronounced reentrance occurring in this diagram. A similar phase diagram has been obtained in the ferromagnetic spin-3 2 BEG model within the MFA [8], the EFT [9] and the CVMPA for the coordination number q < 6 [10], as well as the exact formulation of the model on the Bethe lattice by using the exact recursion equations [12,13] for q < 6, but only differs in that the reentrant behaviour does not exist in these two works. However, the exactly similar phase diagram was obtained for q > 6 in [10] and [13].…”

“…The other phase diagram, Fig. 5b, is a new phase diagram topology, which is either absent from previous approach, namely [13] or has gone unnoticed. Figure 6 Figure 6.…”

“…Recently, Ekiz et al [12] investigated the ferromagnetic spin- [13] extended the previous work for the presence of an external magnetic field [12]. He presented one phase diagram in the (kT / The purpose of the present paper is to study the temperature dependence of order parameters of the twosublattice ferromagnetic spin-3 2 BEG model for different values of interaction parameters and an external magnetic field, to calculate the global phase diagrams of the spin-3 2 BEG model in the absence and presence of the external magnetic field in detail, and to compare the results with the approximate methods [8 -11] and the exact results on the Bethe lattice [12,13]. These calculations have been carried out by using the lowest approximation of the cluster variation method (LACVM) [14], which is identical with the MFA.…”