Spin-1 Ising model with biquadratic exchange interaction in an external magnetic field: A theoretical study within the mean-field approximation

Abstract

The spin-1 Ising model with bilinear and biquadratic exchange interactions in an external magnetic field is studied on a simple two-dimensional square lattice within the mean-field approximation. The obtained results show the existence of dipolar or quadrupolar order, depending on the variation in the strength of the two types of interactions in the absence of a magnetic field. Furthermore, the influence of the external magnetic field on these order is also investigated in detail. These results are analyzed through the presence of spin-1 states with nonzero magnetic moment (i.e., S^z = \pm 1) and zero magnetic moment (i.e., S^z = 0).