Critical phenomena in a two-dimensional ferrimagnetic system: Monte Carlo and Mean-Field Analysis

The critical, first order, and spin compensation behaviors of a ferrimagnetic Ising system, consisting of spins S=3∕2 and Q=5∕2 alternating on a square lattice, have been studied by Monte Carlo (MC) simulations and Mean-Field Theory (MF). The system is defined by a Hamiltonian (H) that contains ferromagnetic next-nearest-neighbors interactions between S spins (J2′) and Q spins (J3′), as well as external magnetic field (h′) and anisotropy (D1′, D2′) interactions. The effects of D1′ crystal and h′ magnetic fields on the critical, double first order transition, and compensation phenomena are analyzed in detail. We found that the existence of a double first order phase transition depends on the temperature and the strength of h′.