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In this work, we have performed Monte Carlo simulations to study a mixed spin-1 and spin-3/2 Ising ferrimagnetic system on a square lattice with two different random single-ion anisotropies. This lattice is divided in two interpenetrating sublattices with spins S A = 1 in the sublattice A and S B = 3 ∕ 2 in the sublattice B . The exchange interaction between the spins on the sublattices is antiferromagnetic ( J < 0 ). We used two random single-ion anisotropies, D i A and D j B , on the sublattices A and B , respectively. We have determined the phase diagram of the model in the critical temperature T c versus strength of the random single-ion anisotropy D plane and we shown that it exhibits only second-order phase transition lines. We also shown that this system displays compensation temperatures for some cases of the random single-ion distribution. [ABSTRACT FROM AUTHOR]

Abstract: We study the effect of two different single-ion anisotropies in the phase diagram and in the compensation temperature of mixed spin-2 and spin- Ising ferrimagnetic system. We employed the mean-field theory based on the Bogoliubov inequality for Gibbs free energy. We use the Landau expansion of free energy in the order parameter to describe the phase diagram. In the temperature versus single-ion anisotropy plane the phase diagram displays tricritical behavior. The critical and compensation temperatures increase with increasing values of the single-ion anisotropies. [Copyright &y& Elsevier]

Abstract We have studied the effects of the random transverse single-ion anisotropy in the phase diagram and in the thermodynamic properties of the spin − 1 Blume–Capel quantum model, which has been used the approach the mean-field theory based on the Bogoliubov inequality for the Gibbs free energy. The phase diagrams were obtained in the temperature τ = k B T ∕ z J versus single-ion anisotropy δ x = D x ∕ z J plane for several values of δ y = D y ∕ z J , p and q. The results show that there is a tricritical behavior only in the range of δ y given by − 0. 048 ≤ δ y < 0. 5. This behavior is shown again by the curves of the magnetization m as a function of temperature τ with corresponding values of δ y , p and q. Highlights • Several phase diagrams were obtained for the spin-1 Blume–Capel quantum model. • The influence of the random single-ion anisotropies was examined for the system. • First- and second-order phase transition lines were found. • The tricritical behavior was examined. [ABSTRACT FROM AUTHOR]

We have studied the effects of two different random single-ion anisotropies in the phase diagram and on the critical properties of a mixed spin-2 and spin-5/2 Ising ferrimagnetic system. We employed the mean-field theory based on the Bogoliubov inequality for the Gibbs free energy. We have used the Landau expansion of the free energy in the order parameter to describe the phase diagram. We have shown that the phase diagram temperature as function of random single-ion anisotropy displays tricritical behavior. We also investigated the existence and dependence of a compensation temperature on random single-ion anisotropies. The critical and compensation temperatures increase with increasing of the random single-ion anisotropies values. [ABSTRACT FROM AUTHOR]