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By using the effective field theory (EFT), the mixed spin-1/2 and spin-3/2 Ising ferrimagnetic model adapted to a double perovskite structure has been studied. The EFT calculations have been carried out from Ising Hamiltonian by taking into account first and second nearest-neighbors interactions and the crystal and external magnetic fields. Both first- and second-order phase transitions have been found in phase diagrams of interest. Depending on crystal-field values, the thermodynamic behavior of total magnetization indicated the compensation phenomenon existence. The hysteresis behaviors are studied by investigating the reduced magnetic field dependence of total magnetization and a series of hysteresis loops are shown for different reduced temperatures around the critical one. [ABSTRACT FROM AUTHOR]

Abstract: Using Monte Carlo simulations with the Metropolis algorithm, we have studied the influence of crystal-field interaction on the critical behavior of magnetic spin-1 Ising film on a cubic lattice structure. The phase diagrams in the plane are obtained for different values of the crystal-field interaction. We found that the special point , at which the critical temperature is independent of the film thickness N, is independent of the crystal-field interaction and that the system may exhibit a tricritical behavior. [Copyright &y& Elsevier]

Within an effective field theory we investigate the anisotropy of an antiferromagnetic coupling and the Ne´el temperature in a diluted spin-7/2 Ising model. The bond dilution (p) effect in the Ne´el temperature is shown in (TN,p) plane for some selected values of anisotropic parameter αc=Jc/J. The temperature dependence of the magnetic moment has been studied for some values of p and αc. [Copyright &y& Elsevier]

Abstract: Monte Carlo simulation has been used to study the magnetic properties and hysteresis loops of a single nanocube, consisting of a ferromagnetic core of spin- surrounded by a ferromagnetic shell of spin-1 with antiferromagnetic interface coupling. We find a number of characteristic phenomena. In particular, the effects of the shell coupling and the interface coupling on both the compensation temperature and the magnetization profiles are investigated. The effects of the interface coupling on the hysteresis loops are also examined. [Copyright &y& Elsevier]

Abstract: Using Monte Carlo simulations, we have studied the influence of surface defects on the critical behavior of magnetic spin- Ising film on a cubic lattice structure. We derive the phase diagram and the critical exponent β in the case of a perfect surface. In such films, the critical temperature can shift to either lower or higher values compared to the corresponding bulk one. In the case of a surface with random, ‘weak’ or ‘strong’ interactions between neighboring spins, it is found that the critical exponent β 1 follows very closely that of the perfect surface case. Far from the critical temperature, the effective exponent decreases with increasing the concentration of strong interactions p. [Copyright &y& Elsevier]