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The Monte Carlo simulation (MCS) technique has been used to study the phase diagrams and the magnetic properties of a cylindrical core/shell spin 1/2 Ising nanowire. The system mainly consists of two parts: the core and the surface shells, and the core is surrounded by the surface shell. The effects of the surface parameters and the random longitudinal field, on the critical and compensation behaviors, are examined. The results present rich critical behavior, which includes the first- and second-order phase transitions. It is also found that the compensation point can appear for appropriate values of the system parameters. The hysteresis curves are obtained for different temperatures (T). The triple hysteresis loops can be seen in the system for antiferromagnetic interactions. The effective filed theory (EFT) results are compared to those obtained by using the Monte Carlo Simulations. However, EFT predicts the same topology of the phase diagrams as the Monte Carlo Simulations. [ABSTRACT FROM AUTHOR]

Within the effective field theory (EFT) with a probability distribution technique that accounts for the self spin correlation functions, the magnetic properties such as the hysteresis loops, susceptibility and magnetization of a spin-1 Ising system with effects of a biaxial crystal field are studied. The effects of the biaxial crystal field on the magnetic properties are discussed and numerical calculations are performed and analyzed for the cases of the honeycomb lattice. A number of interesting phenomena such as the shape of the hysteresis loops and the susceptibility have been found. [ABSTRACT FROM AUTHOR]

Abstract: We have used the effective field theory based on probability distribution method to investigate the hysteresis behavior of the magnetic nanowires with core/shell morphology in a random magnetic field. The hysteresis curves are obtained for different values of the random magnetic field, both ferromagnetic and antiferromagnetic couplings between the shell and the core are considered. A number of characteristic behaviors are find, such as the existence of double or triple hysteresis loops for appropriate values of the system parameters affected by the random magnetic field, temperature, and interfacial coupling. [Copyright &y& Elsevier]