Search

Using Monte Carlo simulations, magnetic properties of the ferromagnetic nanoparticles of Ising spin-1 are investigated in the framework of the Ising model. The system is considered to have a Rubik’s cube structure composed of nanocubes having an equivalent exchange coupling, while, between adjacent nanocubes, the exchange coupling is assumed to vary. Both size effects and system parameters’ influence on phase diagrams of the nanosystem are studied. Thus, the magnetic properties of the system such as the critical temperature, the magnetization, and the coercive field are computed. [ABSTRACT FROM AUTHOR]

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: We study the influence of the surface of the ferroelectric films on the properties of the intrinsic ferroelectric polarization state in frame of statistical Transverse Ising Model (TIM). The quality of the surface is modelled by the dilution parameter that reflects the relative weight of the paraelectric impurities vs. ferroelectric ions. Using the effective field approach the variation of the average value of spontaneous polarization as function of temperature for different film thicknesses has been investigated as function of dilution parameter . The phase diagram of the system and crossover from the ferroelectric to the paraelectric phase is discussed. [Copyright &y& Elsevier]

The influence of a non-perfect surface on the critical properties of magnetic spin-1/2 Ising film on a cubic lattice structure is studied using Monte Carlo simulations based on Metropolis algorithm. The surface magnetization and the surface effective exponent have been studied for several concentration p. Far from the critical temperature, the surface effective exponent βeffs decreases with increasing the concentration p. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulation with the Metropolis algorithm, we have studied the critical behaviour of magnetic spin 1/2 Ising film on a cubic lattice structure. We drive the effective exponent of the each layer βeff(z,t) and of the film βefff (t) as a function of reduced temperature t. A particular attention is paid for the evaluation of the variation of the critical exponents with the film thickness. [ABSTRACT FROM AUTHOR]

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]