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A mixed spin-1 and spin-2 Ising ferrimagnetic system is investigated on a square lattice of spins S = ± 2 , ± 1 , 0 and Q = ± 1 , 0 in the presence of an h ′ external magnetic field, such that S and Q are nearest-neighbors antiferromagnetically coupled. Using Monte Carlo simulations we calculate the finite temperature phase diagrams of the magnetization and the specific heat. We consider ferromagnetic interactions between next-nearest neighbors, S spins ( J 2 ′ ), as well as between the Q spins ( J 3 ′ ), and crystal field and external magnetic field interactions at each point of the lattice. Under these conditions the system exhibits spin compensation temperatures and a first-order reentrant behavior in a certain range of the parameters of the Hamiltonian. We analyze the behavior of the critical and compensation temperatures, as well as the first order phase transition temperatures, with the external magnetic and crystal fields, and the next-nearest neighbors interaction between S spins. We found that the existence of compensation temperatures and a first order phase transition depends on the strength of h ′ , J 2 ′ and D ′ . [ABSTRACT FROM AUTHOR]

The magnetic properties of the mixed spin-1 and spin-5/2 Ising ferrimagnetic model on a hexagonal lattice have been studied using the Monte Carlo simulations. The hexagonal lattice study is formed by alternate layers of spins σ = 1 and S = 5 ∕ 2 . The thermal variations of the magnetizations are given. The magnetic hysteresis cycles are established for different values of exchange interactions, crystal-field and temperatures. The magnetic coercive field is deduced. [ABSTRACT FROM AUTHOR]

We study the thermodynamic and magnetic properties of an Ising bilayer ferrimagnet. The system is composed of two interacting non-equivalent planes in which the intralayer couplings are ferromagnetic while the interlayer interactions are antiferromagnetic. Moreover, one of the planes is randomly diluted. The study is carried out within a Monte Carlo approach employing the multiple histogram reweighting method and finite-size scaling tools. The occurrence of a compensation phenomenon is verified and the compensation temperature, as well as the critical temperature for the model, are obtained as functions of the Hamiltonian parameters. We present a detailed discussion of the regions of the parameter space where the compensation effect is present or absent. Our results are then compared to a mean-field-like approximation applied to the same model by Balcerzak and Szałowski (2014). Although the Monte Carlo and mean-field results agree qualitatively, our quantitative results are significantly different. [ABSTRACT FROM AUTHOR]