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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]

The main objective of this paper is to evaluate the physical properties of Fe 3 S 4 material. To do so, Ab-initio calculations and Monte Carlo Simulations (MCS) by means of the mixed spin model have been used. Fe 3 S 4 compound is formed by two magnetic sub-lattices, one occupied the A tetrahedral with spin 5/2 and the other occupied by B octahedral with both spin 2 and 5/2. The density of states (DOS) has been investigated and confirmed that the compoundis a half metal. Further, the magnetization, susceptibility and specific heat curves have been determined for different sizes of the systemand fromwhich the values of critical exponentsand the critical temperature (T c) have been calculated. Besides, the temperature-dependent magnetization for different values of crystal field has been analyzed to provide an insight into the relation compensation phenomena and crystal field effect. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulations, we studied phase diagrams and magnetic properties of a ferromagnetic/antiferromagnetic Ising nanoparticles assembly with the spin-1/2 core and spin-3/2 shell. The system consists of nanocubes with equivalent exchange couplings of core and shell. However, the exchange couplings between the adjacent spins of the core and shell and between the nanocubes are assumed to vary. Thus, the effects of the exchange couplings and the system size on the phase diagrams are analyzing. Interesting behaviors are found when investigating the critical behavior of the system, the magnetizations, the magnetic susceptibility and the hysteresis loops. The increase of the core/shell size involves that of the temperature one. In addition, the increase in positive exchange interactions between the spins of the core and shell, on the one hand, and between the nanocubes, on the other hand, also increase the critical temperature, which favors the stable phase (3/2, 1/2). • Monte Carlo Simulation is used to study the magnetic properties of an assembly of cubic Core-Shell nanoparticles. • Phases diagrams of critical temperature with the exchange interactions and anisotropy parameter have been studied. • The increase of positive J2/J1 and J4/J1 increase the critical temperature, favoring the stable phase (3/2, 1/2). • Core and Shell sizes, anisotropy and interactions parameters effects on Magnetic hysteresis cycles are given. • Dependent coercivity with sizes and parameters of interactions are found. [ABSTRACT FROM AUTHOR]

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]

Abstract: The present study concerns the system 0.5[xNa2O–(1− x)Li2O]–0.5[0.4(MoO3)2–0.6P2O5], with x varying between 0 and 1. The elaborated glass samples have been characterised using powder X-ray diffraction (XRD), differential thermal analysis (DTA) and impedance spectroscopy. The total alkali oxide content is chosen in order to ensure that the electrical conductivity of the glasses under study is entirely ionic. It was evidenced that the conductivity minimum corresponds to the maximum of the activation energy. The glass transition temperature seems to present a minimum for the ratio Na/(Na+Li)=0.5. On the other hand, the density appears very linearly versus Na/(Na+Li). The mixed alkali effect (MAE) is resulting here in a conductivity minimum observed for the composition corresponding to Na/(Na+Li)=0.5, (x =0.5). It could be attributed to the fact that the two types of alkali ions are randomly mixed and have distinct conduction pathways. This implies that Li ions tend to block the pathways for the Na ions and vice versa. [Copyright &y& Elsevier]