Static properties of spin-crossover with magnetic interaction of Spin-1 Blume-Emery-Griffiths model for two-sublattices

Abstract

The static properties of the spin-1 Blume-Emery-Griffiths (BEG) model for two-sublattices with the presence of an external magnetic field for spin-crossover (SCO) and magnetic ordering are presented. To study the static properties of SCO and magnetic ordering we use the cluster variation method in the lowest approximation (CVMLA). The obtained self-consistent equations are solved using the Newton Raphson method. From these solutions of the self-consistent equations, we present the thermal behaviors of the high-spin fraction (nHS = QA+QB 2 ) state and magnetizations (MF = MA+MB 2 ) for different values of magnetic interaction and quadrupolar interaction parameters. Also, the properties of SCO and magnetic ordering for varying external magnetic fields are presented. It is shown some properties that magnetization is zero and SCO exhibits a first-order phase transition when the temperature increases for different value of magnetic interaction and when temperature decreases both magnetization and SCO are exhibiting the first-order phase transition with the absence of the external magnetic. SCO is different when the temperature is decreasing. However, different states appear for magnetization and SCO with varying external magnetic field for fixed temperature. Our results were compared with other theoretical investigations also given.