Thermomagnetic Behavior of a Ferrimagnet of High Spins: Monte Carlo Analysis

We investigate some critical phenomena of a Ising ferrimagnetic system on a square lattice with spins Q = ±7/2, ±5/2, ±3/2, and ±1/2 in a B sublattice and spins S = ±5/2, ±3/2, and ±1/2 in a A sublattice in presence of an h' external magnetic field, such that Q and S are the nearest-neighbors ferrimagnetically coupled. Using Monte Carlo simulations, we calculate the finite-temperature phase diagrams of magnetization, specific heat, and magnetic susceptibility of the model. The system is defined by a Hamiltonian (1-I) that contains ferromagnetic next-nearest-neighbors interactions between S spins (J'
₂
), as well as external magnetic field and anisotropy interactions at each point of lattice. For a defined range of parameters in 1-I, the system exhibits discontinuities in their physical variables and spin compensation behaviors. In the planes J'
₂
- k
_B
T' and h' - k
_B
T', we analyze the relationship between the critical, compensation, and discontinuous phase transition temperatures with the external magnetic field and the next-nearest-neighbors interaction between S spins. We found that the existence of discontinuous phase transition depends on the strengths of h' and J'
₂
.