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We studied some magnetic behaviors of the Ising model in a single-wall mixed spin (σ = ½, S = 1) triangular nanotube using the effective field theory with correlations (EFTC), and the differential operator technique (DOT). The effects of exchange interactions as well as the temperature and the applied field on the magnetic properties of the nanotube, such as isotherm and spontaneous magnetizations, were carefully analyzed. We demonstrated that the low-temperature behavior of the magnetization is very sensitive to the exchange interactions involved, especially in the case of competitional couplings. Besides the phase diagram, unusual phenomena have been discovered, especially for opposite exchange interactions where magnetization plateaus and frustration are observed. Several forms of ferrimagnetism have been revealed for judicious choices of exchange and single-ion anisotropy. One of the most notable effects is the occurrence of magnetization jumps and fractional plateaus due to both the geometry and the competition between exchange couplings, on the one hand, and the applied magnetic field, on the other hand. Such plateaus could provide a path toward potential applications of functional ferrimagnets in spintronics and device regulation. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulations under the Metropolis algorithm, the magnetic properties of a Mixed Spins (3/2, 1) cubic lattice modeled by mixed spin Ising model have been investigated. First, we discuss the ground state phase diagrams at zero temperature corresponding to different parameters of the model. Then, by choosing ferrimagnetic phases found in the obtained phase diagrams, we analyze the magnetization and compensation behaviors in our system. Striking results have been found; especially, the competition between exchange coupling interactions generates a critical temperature T C and a compensation temperature T comp with T comp < T C . Moreover, the presence of crystal and external magnetic fields leads to the appearance of a second compensation temperature with T c o m p 1 < T c o m p 2 ≪ T C . [ABSTRACT FROM AUTHOR]

The behavior of thermal hysteresis of 2-D hexagonal spin-crossover nanosystem was studied on the basis of microscopic approach, using an Ising-like model. The results were obtained using Monte Carlo method based on the Metropolis algorithm. In the framework of the considered model, a relation between the system size and interaction strength of the neighbor spin-crossover molecules was established. By applying external pressure, a narrowing of the system's hysteresis and a shift of the transition curves toward higher temperature were observed. The application of pressure also leads to a switching between the HS and LS states of the system, which makes such system promising and desirable in sensor applications (as pressure sensors). The influence of the defects on the system transition curves was investigated. Presence of which leads to the narrowing of the hysteresis width. The obtained results of numerical simulations are in accordance with available theoretical and experimental ones of other authors. [ABSTRACT FROM AUTHOR]

We have employed first-principles calculations of density functional theory (DFT) with GGA and GGA+U exchange correlation to study structural, magnetic, and electronic properties of chromium nitride (CrN) in the rock salt (NaCl) structures. The obtained data from DFT calculations is used as an input in high-temperature series expansions (HTSEs) combined with the Padé approximants (PA) method and Monte Carlo simulation (MC) for the Ising model to investigate the magnetic properties of CrN. The obtained results show that CrN is more stable in the antiferromagnetic order, and undergoes structural and magnetic transitions from an antiferromagnetic NaCl structure to a nonmagnetic Pnma phase at 201 GPa. The density of states (DOS) with GGA approach shows that CrN has a metallic behavior in both FM and AFM configurations whereas with GGA+U CrN is semiconductor in AFM and half-metallic in FM order. The Neel temperature (TN) obtained by HTSE and MC is in agreement with available experimental data. [ABSTRACT FROM AUTHOR]

In this work, the phase transitions, for a molecular-based magnet, are examined using mean field method (MFM). The longitudinal magnetizations can be achieved by minimizing the free energy is an interesting function for locating and induction of spin compensation temperatures as well. By applying Blume-Capel (BC) configuration to a system consisting of two sublattices for a mixed spin-3/2 and spin-7/2on a square lattice in the anisotropies plane, the ground-state phase diagram of this system has been built. On principles of Bogoliubov inequality (BI) of the free energy, it has been investigated the spin compensation phenomena. In particular, characteristic ferrimagnetic features have been shown depending on an unequal crystal field parameters (DA, DB<-1.0) applied on the A−sites and B−sites, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the structural, electronic, and magnetic properties of the cubic perovskite system Mn4N using the first principles calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA). The obtained data from DFT calculations are used as input data in Monte Carlo simulation with a mixed spin-5/2 and 1 Ising model to calculate the magnetic properties of this compound, such as the total, partial thermal magnetization, and the critical temperatures (TC). The obtained results show that Mn4N has a ferrimagnetic structure with two different sites of Mn in the lattice and presents a metallic behavior. The obtained TC is in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Critical behavior and magnetic properties of La0.67Sr0.33MnO3 (symbolized as LS33MO) have been studied by means of Monte Carlo simulation (MCS). By using the heat-bath algorithm and the Ising model up to third nearest neighbor exchange interactions, we have computed the magnetic and magneto-caloric properties. The effects of the temperature (T) and the external magnetic field (h) on the magnetic behavior of LS33MO have been discussed. The results demonstrate that the Curie temperature (TC) is close to the experimental value. The magnetic entropy shows a maximum value around TC which increases linearly with the rise of the external field h. For h = 5T, the maximum entropy (∆ S m max ) is about 3.67 J K−1 kg−1 which is in good agreement with the experimental results. The relative cooling power (RCP) has been estimated and it has been found that it increases with respect to the external field. The predicted critical behavior has been studied by isothermal magnetization of LS33MO nanoparticle compound. The critical exponents (Crt.Exps) are determined by various approaches, such as the modified Arrott plot (AP) and critical isotherm ways. Therefore, the Crt.Exp values obtained by different techniques are β = 0.306, γ = 1.178, and δ = 4.025 respectively. The trustworthiness of the values of the Crt.Exp was approved by the Widom scaling equation and the universal scaling hypothesis. [ABSTRACT FROM AUTHOR]

In the presence of the crystal field D/JCore and the external magnetic field h/JCore, using the Monte Carlo (MC) simulation based on the heat bath algorithm and the effective field theory (EFT), the triangular mixed spin nanowire model consisting of a spin-(1/2) core which is encircled by a spin-1 ferrimagnetic surface shell is studied. We have studied the special effects of the core surface and crystal field on the critical and compensation temperatures. Several properties, such as the magnetization, hysteresis behaviors, coercive field, and remanent magnetizations are studied. For the appropriate values of the system parameters, the compensation point and multi-loops are found PACS 05.50. + q; 77.80. Bh. [ABSTRACT FROM AUTHOR]

The effects of single-ion anisotropies and an external magnetic field on the magnetization of the mixed-spin (7/2, 3/2) ferrimagnetic Ising system are investigated within Monte Carlo simulation. Under certain values of the physical parameters, multiple hysteresis loop behaviors such as double, triple, and quintuple hysteresis cycles have been observed. Particularly, the superparamagnetic phase has been shown. The ground-state phase diagrams are presented. [ABSTRACT FROM AUTHOR]

A Monte Carlo simulation based on Metropolis algorithm has been used to investigate the magnetic properties of an Ising ferrimagnetic nanowire on a hexagonal structure, which is made up with L alternate layers of spins σ = ±3/2, ±1/2 and S = ±1, 0. The critical behaviors are studied, in the absence as well as in the presence of crystal field interactions. The obtained results show the existence of some interesting phenomena, such as the appearance of different types of phase diagrams. Furthermore, tricritical point, isolated critical point, critical end point, and compensation behavior are found for appropriate values of the system parameters. [ABSTRACT FROM AUTHOR]