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A hexagonal nanowire consisting of a ferromagnetic spin- 1 2 core, spin-1 inter core/shell and spin- 3 2 outer shell coupled with ferrimagnetic interlayer couplings has been studied by the use of Monte Carlo simulation based on the heat bath algorithm. The exchange interactions and the uniaxial anisotropy effects on the magnetic properties of the system have been discussed. We found that, the system exhibits the compensation phenomenon, the first and the second order transitions. Moreover, we have obtained that, the existence of the tricritical point depend on the surface shell interaction. [ABSTRACT FROM AUTHOR]

Realizing room-temperature ferromagnetic interactions in diluted magnetic semiconductors is a precondition for the future application of next-generation spin-based information technologies. However, finding effective strategies to alter the inherent magnetic coupling remains difficult. This paper aims to propose an approach for manipulating the ferromagnetism of (0.12%, 0.18%, 0.25%) V-doped ZnO (V-ZnO). The influence of V doping on the structural, electronic, and magnetic properties of ZnO is studied using first principles pseudo-potential plane wave method within the density functional theory (DFT). According to the first-principles calculations, the ferromagnetic ground state is maintained by a half-metallic electronic structure resulting from substantial hybridization between V-3d and O-2p electrons, and the calculations suggest that the ferromagnetism could be governed by the interactions between cluster spines in the VO4 tetrahedra. With the magnetic coupling strengths obtained by the green's function method with the Wannier functions as a localized basis, the Monte Carlo simulation based on the Classical Ising model predicts the ferromagnetism of Zn 1 − x V x O (x = 0.12%, 0.18%, 0.25%) with T c = 55 K, 165 K and 345 K. The observed results show that, as a diluted magnetic semiconductor, V-doped ZnO is an excellent candidate. • Zn 1-x V x O with (x = 0.12, 0.18, and 0.25) exhibits a half-metallic ferromagnetic behavior. • Shifting of E f into the conduction band proves that V-doped ZnO is n-type semiconductor. • Monte Carlo simulation shows that V doped ZnO exhibits a T c above the room temperature. • Hysteresis loop become larger with the concentration of the V impurities. [ABSTRACT FROM AUTHOR]

A Monte Carlo simulation with heat bath algorithm is used to study the effect of random crystal field and surface exchange interactions on the critical behavior and the magnetic properties of a spin-1 Ising ferromagnetic thin film having the simple cubic symmetry. The phase diagram exhibits a rich variety of behaviors such as the double reentrant phenomena and the existence of tricritical points. Thermal magnetization behavior and phase diagrams have been discussed in detail. [ABSTRACT FROM AUTHOR]