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• 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]

The magnetic properties of spins -S and σ Ising model on the Bethe lattice have been investigated by using the Monte Carlo simulation. The thermal total magnetization and magnetization of spins S and σ with the different exchange interactions, different external magnetic field and different temperatures have been studied. The critical temperature and compensation temperature have been deduced. The magnetic hysteresis cycle of Ising ferrimagnetic system on the Bethe lattice has been deduced for different values of exchange interactions between the spins S and σ , for different values of crystal field and for different sizes. The magnetic coercive filed has been deduced. [ABSTRACT FROM AUTHOR]

• The mixed spin Ising model is generally used as a modeling tool to study ferrimagnetism. • Monte Carlo simulation to study the critical and the compensation behaviors of a cubic lattice considering a mixed spin- 3/2 and spin-1 Ising ferrimagnetic model. • The presence of crystal and external magnetic fields is not sufficient to generate the compensation phenomenon in a mixed spins. In this study, we perform Monte Carlo simulations to study the magnetic properties of a mixed Ising model on a cubic lattice where spins S i A = 1 and σ J B = 3/2 are located in sublattice A and B, respectively. The proposed Hamiltonian includes coupling to nearest-neighbors interactions, next-nearest-neighbors interactions, crystal fields D S and D σ and external magnetic field h. We perform exact ground-state calculations for our model. The obtained results show the behavior of the critical temperature with the presence of the compensation temperatures under a certain range of parameters. Particularly, we found that the existence of compensation temperatures depends on the strength of the coupling to the next nearest neighbors between the S i A spins and between the σ J B spins, and it appears in a certain range of values of the external magnetic and crystal field of different spins. [ABSTRACT FROM AUTHOR]

• Critical properties of Fe-Al alloys in the bcc phase – phase diagram. • Ising model with exchange and superexchange interactions. • Monte Carlo simulations taking the effects of the Al cluster sizes. A spin-1/2 Ising model, defined in the body centered cubic lattice, is used to describe some of the thermodynamic properties of Fe p - Al q alloys, with p + q = 1. The model assumes, besides the nearest-neighbor exchange coupling, the existence of further next-nearest-neighbor superexchange interactions, where the latter ones depend on the aluminum atoms cluster size. The Ising system so considered is studied by employing Monte Carlo simulations, using a hybrid algorithm consisting of one single-spin Metropolis move together with one single-cluster Wolff algorithm allied, in addition, with single histograms procedures and finite-size scaling techniques. Quite good fits to the experimental results of the ordering critical temperature, as a function of Al concentration in the range 0 ⩽ q < 0.7 , are obtained and compared to more recent theoretical approaches done on the same alloys. [ABSTRACT FROM AUTHOR]