Search

• The critical temperature of FeNi and FePt alloys using Heisenberg interaction is closer to the experimental value than the Ising interaction. • The FeNi and FePt alloys prefer a ferromagnetic phase over the ferrimagnatic phase. • The Ising interaction predicts higher critical temperature for the FeNi alloy than the Heisenberg interaction. • The Heisenberg interaction predicts higher critical temperature for the FePt alloy than the Ising interaction. A Monte Carlo simulation has been used to explore the magnetic properties of L1 0 ordered FeNi and FePt binary alloys. Our Hamiltonians include Heisenberg interaction or Ising interaction. Our calculations of variations of specific heat C v , magnetic susceptibility χ and the magnetization M with the temperature T showed that predicted critical temperature for ferromagnetic phase is very close to the experimental values for these alloys. Also, thermal hysteresis loops, magnetic remanence, and the coercive field have been calculated. Moreover, the magnetic properties of the ferrimagnetic phase are presented. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation has been applied to study the thermal and magnetic properties of the inverse spinel-like structure, copper fluoride as an example, of spin 1/2 - spin 1 Ising interactions. Our calculations of the magnetization as a function of temperature shows compensation for low values of coupling strength between spin-1 type atoms (J 1) in the same layer, low absolute value of coupling strength between the layers of different spin type (J 3), and large values of coupling strength between spin-1/2 (J 2). The transition from ferrimagnetic to paramagnetic phase is observed at the critical temperature T c. In addition, T c increases slowly at different values of the exchange interaction. Regarding the anisotropy field D on spin 1 state, our results show a threshold value of −0.3 for the compensation to appear. Finally, our results are applicable to the Cu 2 F 5 compound which has d8 and d9 electron configurations. • The compensation temperature in the ferrimagnetic phase depends on the strength of the spin-spin interactions • Compensation occurs for small values of coupling strength of the same type atoms • Compensation occurs for large values of coupling strength of the different type atoms • An itinerant region has been revealed between the compensation and critical temperatures. [ABSTRACT FROM AUTHOR]

• Mixed spin Ising model on a checkerboard square structure was proposed. • The effect of crystal field and exchange coupling were studied. • The phase diagrams of the critical and compensation temperatures were presented. • Double-loop hysteresis behaviors were found. The magnetic properties and phase diagrams of the mixed spin-1 and spin-1/2 Ising model on a checkerboard square structure have been studied using the Monte Carlo simulations based on the Metropolis update protocol. The system consists of four quartets of alternative spin configurations. We found that the compensation temperature evolves for J 1 <0.6 of the spin-1 assembly and J 2 >1.6 of spin-1/2. Regarding the crystal field strength, a threshold value of D > - 0.8 has been observed. We obtain the N -, Q - and P -type compensation behaviors in the system. The phase diagrams exhibit a second-order phase transition to a paramagnetic phase for small values of D ; hence, the system does not show the tricritical point. However, for large negative values of D a first-order phase transition occurs at the threshold value of J 1. The magnetic hysteresis cycles have been obtained for different values of the exchange interaction, temperature, and crystal field. Finally, the system exhibits the superparamagnetic behavior for a fixed value of the temperature and crystal field. [ABSTRACT FROM AUTHOR]