The magnetic properties of a small particle on an hexagonal substrate: Monte Carlo and effective field treatments

The Monte Carlo Simulation (MCS) and the Effective Field Theory (EFT) have been used to study the magnetic properties of a small particle on an hexagonal substrate at temperatures below, around and above the critical temperature. The system is described by a mixed-spin Ising model in which the σ=1/2 and S=1 spins are distributed in concentric and alternate hexagonal rings. The hysteresis curves are obtained for both cases: ferromagnetic and ferrimagnetic system. We find that the hysteresis loop areas decrease when the temperature increases, and the hysteresis loops disappear at certain temperatures. Moreover, as the temperature increases, the hysteresis loop areas disappear earlier for the ferromagnetic substrate than the ferrimagnetic one. The thermal behaviors of the coercivities and the remanent magnetizations are investigated. The effect of the intrasublattice exchange interaction on the compensation phenomenon is also examined.