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The sandwiches of magnetic/nonmagnetic/magnetic (M/NM/M) materials have been investigated combined with Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange interactions with mixed apins-2 and 3/2 using Ising model using Monte Carlo simulations. The RKKY value is obtained for different distance between the different magnetic and non magnetic multilayer. The RKKY exchange interactions as a function of distance between the magnetic multilayer have been given. The magnetizations and magnetic susceptibilities of each magnetic bloc are obtained. The reduced critical temperatures of each bloc and the system are obtained. The reduced critical temperature is obtained for a fixed size. The theoretical calculations showed an oscillating behavior of the magnetic parameters with increasing the nonmagnetic layers. The total magnetization versus the exchange interactions and crystal field in each bloc is established. The magnetic hysteresis cycles are established for a fixed magnetic parameters.

The kinetics of the semi-infinite Ising model in the presence of a time dependent oscillating external field is studied within the framework of the mean-field approach. We use the Glauber-type stochastic dynamics to describe the time evolution of this system. We present a variety of phases in semi infinite cubic ferromagnet with spin 1 at the bulk and spin 1 2 at the surface. The obtained Phase diagrams contains surface ordered phase (BP, SF), completely ordered phase (BF, SF) and completely disordered phase (BP, SP) that strongly depend on interaction parameters. The first or second order nature of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. Furthermore, the system exhibits dynamical tricritical phenomenon. The magnetizations and phase space trajectories are given and discussed.

This work is a study of electronic and magnetic properties of the intermetallic GdFe2Zn20 compound which is realized using the Density Functional Theory (DFT), the mean field approximation (MFA) and the Monte Carlo Simulations (MCS). For the ab-initio calculations, we determined the electronic density of states precisely by the FP-LAPW calculations within the generalized gradient approximation (GGA) where we observed the Dos of the magnetic elements of the compound which are the Gd with S = 7 ∕ 2 and Fe with σ = 2 also the total Dos is determined. We proposed a Hamiltonian for the system and we solved it by the mean field approximation. We compared between magnetization by MFA and MCS. The phase diagrams, the specific heat, and the magnetic susceptibilities, critical exponents of this compound have also been studied.

The half-metallic ferromagnetic of Gallium nitride doped with double impuritiesGa 1 − 2 x Mn x Co x N ( x = 3 % and 6%) has been investigated by means of first principles investigation combined with Monte Carlo Simulation. The stability of the ferromagnetic state is investigated by comparing the total energies to the spin-glass state. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in half-metallic ferromagnetic states with high Neel temperature.

In this work, we have analyzed the behavior of the 2D Ashkin–Teller model with spin-1 under the effect of the quantum transverse field and longitudinal crystal field. However, using mean field theory, three new diagrams of phase are found by varying the crystal field values. On the other hand, three others new phase diagrams with different quantum transverse field values. Therefore, multicritical behaviors are studied as a function of four-spin interaction coefficient ( J 4 ∕ J 1 ) . Moreover, for the objective of assuring the existence of the different phases in the phase diagrams, we have plotted in addition the variation of the transverse field as a function of crystal field.

The magnetic properties of the mixed spin-1 and spin-5/2 Ising ferrimagnetic model on a hexagonal lattice have been studied using the Monte Carlo simulations. The hexagonal lattice study is formed by alternate layers of spins σ = 1 and S = 5 ∕ 2 . The thermal variations of the magnetizations are given. The magnetic hysteresis cycles are established for different values of exchange interactions, crystal-field and temperatures. The magnetic coercive field is deduced.

This work will be focused on the electronic and magnetic properties of Sr2CoUO6 (SCUO) using ab-initio calculations and Monte Carlo Simulation (MCS). Firstly, we calculate the exchange coupling and the crystal field, then, the electronic and magnetic properties will be studied, using the full-potential linearized augmented plane wave (FP-LAPW) method, as implemented in the Wien2k code. This method employing the generalized gradient approximation (GGA) for exchange–correlation term. The half-metallic ferromagnetic nature implies a potential application of this new compound in spintronics devices. Also, we have presented the results of the band structures and densities of states for the two up and down spin polarizations. The exchange coupling and the crystal field calculated are J = 0 . 567 m e V and δ = 0 . 559 meV , and total spin magnetic moments is 2.96 μ B closed to experimental values 3 μ B. Secondly, we have presented the results for the magnetization and the susceptibility as a function of temperature. Finally, we obtain the critical temperature T = 9 . 20 K by MCS in good agreement with the experimental value.

In this paper, an approximation method has been used to calculate Super Exchange (SE) and the Double Exchange (DE) couplings in the Double Perovskite (DP) structure of Sr2CrWO6. The method relies on a relation between internal energy per site and magnetization per site and Monte Carlo simulation in the framework of Ising model. A new model parameter has been proposed and varied to find the exchange couplings that verify the experimental Curie temperature measured under an external field h = 0.01 T . SE coupling has been found equal to −7.554 meV and the DE couplings corresponding respectively to Cr and W ions have been found equal to 17.629 and 5.661 meV. Internal energy per site has been calculated.

We investigate analytically and by numerical simulations, the reentrant low density phase for high injection rate in the Nagel–Schreckenberg model. It is found that the reentrance phenomenon is a direct consequence of our injection strategy. Indeed, by adopting our injection rule, an injection rate exists, above which the in-flow begins to decrease by increasing the injection rate. In addition, we have studied the extraction rate interval at which the reentrance of the low density phase appears. It is found that this interval increases with increasing the maximal velocity. For the non deterministic case, the reentrance interval shifts to higher values of extraction rate.

A bi-layer system consisting of layers of spins (7/2, 3) in a ferromagnetic dendrimer structure, separated by a non-magnetic spacer, is studied by Monte Carlo simulations. The effect of the RKKY interactions is investigated and discussed for such system. It is shown that the magnetic properties in the two magnetic layers depend strongly on the thickness of the magnetic and non-magnetic layers. The total magnetizations and susceptibilities are studied as a function of the reduced temperature. The effect of the reduced exchange interactions as well as the reduced crystal field is outlined. On other hand, the critical temperature is discussed as a function of the magnetic layer values. To complete this study we presented and discussed the magnetic hysteresis cycles.

In this paper, we investigated a non-signalized T-shaped intersection using the cellular automata model under the open boundary condition. Two different priority rules at intersection are introduced (Rule 1, Rule 2) to eliminate the jam-packed state. Phase diagram and its variation with the ratios of right and/or left turning vehicles are investigated. The space-time and the density profiles are also studied. The simulation results indicate that the system does not show the same performance under different priority rules, where Rule 1 (resp. Rule 2) can be better than Rule 2 (resp. Rule 1) according to the ratios of turning vehicles.

The thermal and magnetic properties of the mixed spin-1 and spin-3/2 in the presence of the random crystal field are studied within the mean field approach based on the Bogoliubov inequality for the Gibbs free energy. The model exhibits first, second order transitions, a tricritical point, triple point and an isolated critical end point. It is found that the system displays simple and double compensation temperatures, five topologies of the phase diagrams. A re-entrant phenomenon is also discussed and the thermal dependences of total magnetization according to extended Neel classification have been also given.

We propose an extended cellular automaton model for traffic flow, taking into account lateral interactions with defects and between vehicles. The fundamental diagram for a given defects density on the road is studied. It is found that the plateau size increases linearly with the decreasing road width for little defects densities. Furthermore, the capacity increases linearly with the increasing road width. However, for a fixed road width, the capacity decreases exponentially with the increasing defects density. The lateral effects for non-mutual interactions between lanes and for the same maximal velocity is also investigated. It is found that the lateral effects on one lane are meaningful only when the density on the other lane is above the critical density. However, the lateral effects are always present if fast and slow lanes exist. Little differences have been found for the mutual interactions.

The effect of random crystal-field on the stationary states of the kinetic spin-3/2 Blume–Capel model is investigated within the framework of the mean-field approach. The Glauber-type stochastic dynamics is used to describe the time evolution of the system which is subject to a time-dependent oscillating external magnetic field. In addition to the well-known phase transitions and the appearance of the partly ferromagnetic phase characterized by the magnetization m = 1 in equilibrium case, a new dynamical regions between the ferromagnetic phases F 1 / 2 , F 1 and F 3 / 2 are found where F 3 / 2 + F 1 / 2 , F 3 / 2 + F 1 , F 1 + F 1 / 2 phases coexist for a weak value of the reduced magnetic field ( h ). Whereas for higher value of h both solutions ordered F and disordered P phases coexist. Hence we present six types topologies of phase diagrams which exhibit dynamical first-order, second-order transition lines, dynamical tricritical and isolated critical end points. Furthermore, the dynamical thermal behavior magnetizations, susceptibilities and phase space trajectories are given and discussed.

In this paper we study, using mean field theory (MFT), the effect of the anisotropic Dzyaloshinskii–Moriya (DM) interaction on the phase diagrams of the spin-half Ashkin–Teller model on hypercubic lattice. Different new phase diagrams are found by varying the anisotropy of DM interaction. The multicritical behavior is studied as a function of four-spin interaction coefficient J 4 / J 1 and for two fixed values of spin interaction coefficient J 2 / J 1 .