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A hexagonal nanowire consisting of a ferromagnetic spin– 1 2 core and spin– 3 2 outer shell coupled with ferrimagnetic interlayer coupling has been studied by the use of the Monte Carlo simulation based on the heat bath algorithm. Particular emphasis is given to the effects of the size, the crystal field, the shell and the interface coupling constants on the critical and the compensation phenomenon. Some interesting behaviors have been observed which include the first and second order phase transitions. The isolated critical points are also observed. We have also found that the system exhibits the compensation phenomenon for appropriate values of the system parameters. The critical exponent has also been calculated. [ABSTRACT FROM AUTHOR]

The phase diagrams (critical and compensation temperatures) of a mixed spin Ising nanowire with a negative core–shell interaction and a surface dilution, are studied by using the Monte Carlo Simulation (MCS). Some characteristic phenomena, which depend on the surface parameters, have been found in the phase diagrams. In particular, the behavior of the compensation and the tricritical points are examined by changing the crystal field, the core–shell coupling and the physical parameters at the surface. [ABSTRACT FROM AUTHOR]

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]

Abstract: We have used Monte Carlo Simulations (MCS) to study the hysteresis behavior of the magnetic nanowire with core/shell morphology described by the spin Ising particles in the core and the spin Ising particles in the surface shell. The hysteresis curves are obtained for different temperatures. We find that the hysteresis loop areas decrease when the temperature increases and the hysteresis loops disappear at certain temperatures. Barkhausen jumps are observed for the ferromagnetic nanowire system. An unusual form of triple hysteresis behaviors is observed for the ferrimagnetic nanowire system. The thermal behaviors of the coercivity and the remanent magnetization are also investigated. [Copyright &y& Elsevier]

Abstract: In this work, we have used Monte Carlo Simulation technique (MCS) and effective field theory (EFT) to study the critical and the compensation behaviors of a ferrimagnetic cylindrical nanowire. The system consists of a ferromagnetic spin S A =1/2 core and a ferromagnetic spin S B =1 surface shell coupled with an antiferromagnetic interlayer coupling J 1 to the core. The effects of the uniaxial anisotropy, the shell coupling and the interface negative coupling on both the critical and compensation temperatures are investigated. [Copyright &y& Elsevier]

Abstract: The Monte Carlo Simulation (MCS) and the Effective Field Theory (EFT) have been used to study the magnetic properties of a small particle on an hexagonal substrate at temperatures below, around and above the critical temperature. The system is described by a mixed-spin Ising model in which the and spins are distributed in concentric and alternate hexagonal rings. The hysteresis curves are obtained for both cases: ferromagnetic and ferrimagnetic system. We find that the hysteresis loop areas decrease when the temperature increases, and the hysteresis loops disappear at certain temperatures. Moreover, as the temperature increases, the hysteresis loop areas disappear earlier for the ferromagnetic substrate than the ferrimagnetic one. The thermal behaviors of the coercivities and the remanent magnetizations are investigated. The effect of the intrasublattice exchange interaction on the compensation phenomenon is also examined. [Copyright &y& Elsevier]

Abstract: A Monte Carlo Simulation has been used to study the critical behavior of the magnetic spin-1 Ising nanowire on an hexagonal lattice structure. Our system consists of a ferromagnetic core with two shells, coupled antiferromagnetically with a surface shell. The effects of the crystal field, the shell and the core/shell interactions on the behavior of the system are examined. We found that the system exhibits one or two compensation points, the first and the second order transitions. Moreover, we have obtained that the critical point depends on the shell coupling. [Copyright &y& Elsevier]

In this paper, the hysteresis behavior of the nanotubes, consisting of a ferroelectric core of spin-1/2 surrounded by a ferroelectric shell of spin-1/2 with ferro- or anti-ferroelectric interfacial coupling is studied by using the transverse Ising model (TIM). Based on a probability distribution method, the effective field theory has been used to examine the effects of the interfacial coupling constant, the transverse field, and the temperature on the hysteresis loops of the nanotubes. A number of characteristic behaviors have been found, such as the existence of triple hysteresis loops for appropriate values of the system parameters. The remanent polarization and the coercive field, as functions of the temperature, are examined. [ABSTRACT FROM AUTHOR]

Abstract: The phase diagrams and magnetic properties of a decorated two-sublattices ferrimagnetic Ising models consisting of two magnetic atoms A and B with and are investigated by the use of an effective field theory based on a probability distribution method. The effects of the uniaxial crystal field D (on the B atoms) and the random longitudinal field, on the behavior of the system, are examined. We find a number of characteristic phenomena, such as the possibility of two compensation points, the re-entrant behavior and the existence of tricritical points. [Copyright &y& Elsevier]

By using the effective field theory based on a probability distribution method, the phase diagrams and the magnetic properties of an Ising nanowire in the presence of the biaxial transverse crystal-field are investigated. The effects of the biaxial transverse crystal field, the interfacial coupling and the exchange interaction in the surface on the phase diagram, the magnetization and the internal energy are examined. Some characteristic phenomena are found such as the tricritical behavior, the critical end point and the re-entrant phenomenon. [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]