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In this work, we study the magnetocaloric properties of half 5/2 and integer 3 mixed spin model on a square–hexagon «4-6» structures are studied by Monte Carlo simulations. The total magnetization and the magnetization of each sub-lattice of the mixed-spin lattice have been analyzed. The magnetic susceptibility, dM/dT and magnetic entropy changes are found. The magnetic hysteresis cycles under, with the temperatures, exchange interactions (S-S), (σ-σ) and (σ-S), and the crystal fields (Dσ and DS) has been discussed. [ABSTRACT FROM AUTHOR]

We have employed simulations by Monte Carlo to investigate the magnetic properties and magnetocaloric effect of graphene alternate layers with mixed spins S = 3/2 and σ = 2. The ground state phase diagrams have been obtained. In addition, the impact of the number of layers, the reduced exchange couplings (S–S), and (S–σ), and the crystal field on total magnetizations, magnetic susceptibilities, and magnetic hysteresis cycles have been studied. The compensation and critical temperature were found. The specific heat, the specific heat change, magnetic entropy change and relative cooling power are determined. This system is useful in a variety of spintronic device applications. [ABSTRACT FROM AUTHOR]

In this work, we study the magnetic properties of a nano-borophene structure consisting of mixed spins (S = 2, σ = 5/2) with the defects. We have used the Monte Carlo simulation (MCS) based on the Metropolis algorithm. The ground-state phase diagrams, the critical and compensation temperatures and the hysteresis cycles were also established for several values of defect, temperature, external magnetic, crystal field and exchange interactions. [ABSTRACT FROM AUTHOR]

In this study, we have used Monte Carlo simulations that explain the magnetic properties and magnetocaloric effect of a nano-graphene bilayer separated by non-magnetic layers with mixed spin 3/2 and 3 with RKKY (Ruderman-Kittel-Kasuya-Yosida) exchange coupling. We present and discuss ground state phase diagrams that have been found. Also, the reduced critical temperature is obtained for several values of the number of non-magnetic layers (NM). The system can exhibit a phase transition from the ferromagnetic to the paramagnetic phase at a reduced critical temperature. The effect of the parameter NM, the reduced exchange interactions (S–S), (σ−σ), and the reduced crystal field on the total magnetizations and the established hysteresis loops are investigated. Specific heat, specific heat change, thermal magnetization dM/dT, and magnetic entropy changes as a function of the temperature for various reduced external magnetic fields were investigated in detail. Finally, we report the influence of different values of reduced magnetic field h / J s σ on the relative cooling power. [ABSTRACT FROM AUTHOR]

The zinc oxide ZnO doped with cobalt ZnCoO, and with other impurities such as Ga, and vacant sites (Vc) have been studied to introduce electrons and holes by using the Ab-initio calculations, based on the AkaiKKR (MACHIKANEYAMA) program. These compounds are ferromagnetic above room temperature. In these systems, the ferromagnetic states are stabilized much more by coating the electrons. Zn atoms are substituted by Ga atoms to coat electrons. In this work, we discussed the stability of the ferromagnetic states of diluted magnetic semiconductors and the type of interactions responsible for the stability of systems like ZnO doped by Co and co-doped by Ga. [ABSTRACT FROM AUTHOR]

The dielectric Properties of Borophene superlattices A/B/A/B are studied by Monte Carlo study (MCS). The ground state of Borophene superlattices was found for several values of exchange interactions, crystal and electric fields. The variation of total and partial polarizations with the temperature is given. The critical and compensation temperatures are deduced with exchange interaction between the same spins typed spins different. Finally, the ferroelectric hysteresis loops of Borophene superlattices were given. The obtained results may open the way to experimental researchers and theorists on Borophene superlattices. [ABSTRACT FROM AUTHOR]

The magnetic properties and ferrimagnetic hysteresis loop of azulene-like nano-structure have been investigated via Monte Carlo simulations. The ground state phase diagrams of azulene-like nano-structure with half and integer mixed spins (3;3/2) are found. The multiphase points, disordered regions and various structures are presented. Ground state phase diagrams are useful for checking the reliability of the numerical results for temperature phase diagrams and allow to explore regions where significant magnetic behavior could occur. The transition and compensation temperatures are obtained. The temperature dependence of magnetization is established. From the study of magnetic properties in terms of Arrott plots, we deduced that ferrimagnetic phase transition is of second order in our system. The variation of total magnetization, transition and compensation temperatures with crystal field were obtained. The magnetic hysteresis cycles for several temperatures, exchange interactions between S–S and crystal filed DS are determined. The magnetic properties of azulene-like nano-structure were directly related to the ordering magnetic structure. Here, we show first results for such azulene-like nano-structure. [ABSTRACT FROM AUTHOR]

In this work, we have used the Monte Carlo simulation to study the effect of impurities on the magnetic properties of Mn1-pBi system. Free boundary conditions for our system were applied to simulate Hamiltonian system of Mn1-pBi. The exchange interactions are calculated using the ab initio calculations. The variation of magnetization, magnetic susceptibility, and magnetic specific heat vs. temperature was given for a pure (p = 0) and a several impurities (p) for Mn1-pBi. The critical temperature of Mn1-pBi was determined. The effects of impurities (p), crystal field, and impurities on the magnetic hysteresis cycle were investigated. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the magnetic properties of the MnBi magnetic systems by using the Monte Carlo simulation. Indeed, we analyzed the effect of the number of layers on the magnetic properties of the compound MnBi. The magnetization, the binder cumulant, the Curie temperature, and the hysteresis cycle are also calculated in this work. We used the free boundary conditions to simulate the properties of the studied system, and we presented the effect of multilayer numbers on the magnetic properties of MnBi films. Indeed, the indications that coercive field increases drastically with the increases multilayer numbers is consistent with the experimental facts. [ABSTRACT FROM AUTHOR]

Monte Carlo (MC) simulation method with the Metropolis algorithm is used to study the magnetic and thermal phase transition properties of a spherical nanoparticle. The system consists of two concentric spheres of rays RC and RS, respectively (Rc < Rs). For r < Rc, the spin is σ = ±3 /2 and ±1 /2, and for RC < r ≤ RS, the spin is S = ±7 /2, + 5/2, ±3 /2, and ±1 /2 with antiferromagnetic interface coupling. Between RC and RS, the sites are populated with the probability (p). We present a detailed discussion on the magnetic and thermal phase transition characteristics of the system under consideration. Our investigations show that this system can be used as a magnetic nanostructure possessing potential applications in magnetism. [ABSTRACT FROM AUTHOR]

5-Azidomethyl-8-hydroxyquinoline has been synthesized and characterized using IR, H and C NMR spectroscopic methods. Thermal analysis revealed no solid-solid phase transitions. The crystal structure of this compound was refined by Rietveld method from powder X-ray diffraction data at 295 K. The single- crystal structure of the compound at 260 K was solved and refined using SHELX 97 program. According to the data obtained by both methods, the structure of the compound is monoclinic, space group P2/ c, with Z = 4 and Z' = 1. For the single crystal at 260 K, a = 12.2879 (9) Å, b = 4.8782 (3) Å, c = 15.7423 (12) Å, β=100.807(14)°. Mechanisms of deformation resulting from intra- and intermolecular interactions, such as hydrogen bonding, induced slight torsions in the crystal structure. The optimized molecular geometry of 5-azidomethyl-8-hydroxyquinoline in the ground state is calculated using density functional theory (B3LYP) and Hartree-Fock (HF) methods with the 6-311G( d,p) basis set. The calculated results show good agreement with experimental values. Energy gap of the molecule was found using HOMO and LUMO calculation which reveals that charge transfer occurs within the molecule. [ABSTRACT FROM AUTHOR]