The Ising model in the presence of a random field is investigated within the mean field approximation based on Landau expansion. The random field is drawn from the asymmetric and anisotropic bimodal probability distribution P(hi)=pδ(hi−h0)+qδ(hi+λ∗h0), where the site probabilities p,q...

The effect of random crystal-field on the magnetic properties of the semi-infinite system is investigated by the use of the mean field approximation. In this system, the sites of the surface and bulk are occupied by spin- 1/2 and spin-1, respectively. The appearance of the partly ferromagnetic...

The quantum mechanical version of a classical model for studying the orientational degrees of freedom corresponding to a nematic liquid composed of biaxial molecules is presented. The effective degrees of freedom are described by operators carrying an SU(3) representation, which allows the...

Motivated by spintronic device applications, we engineer a superlattice model based on periodic tri-layers consisting of spins σ=12, S=1 and q=32 residing on the sites of a square lattice, interacting with an external magnetic field. We study its phase diagrams and magnetic properties. We...