Monte Carlo investigation for an Ising model with competitive magnetic interactions in the dominant ferromagnetic-interaction regime

We apply classical Monte Carlo simulation to examine the thermodynamic properties of perovskites described by the Ising model with competitive magnetic interactions. By correspondingly adjusting the ferromagnetic-interaction and antiferromagnetic-interaction probabilities, $p$ and $(1-p)$, in the regime $p \ge 0.5$, the temperature dependence of magnetization, total energy, spin susceptibility, and specific heat consistently show a ferromagnetic to paramagnetic (FM-PM) phase transition at a critical temperature $T_c$. Besides, the inverse susceptibility is confirmed to follow Curie-Weiss's law above another critical temperature $T_{CW}$. By increasing the FM interaction probability, we have observed the FM-PM critical temperature $T_c$ shifted to the higher value while the Curie-Weiss critical temperature $T_{CW}$ moves to the lower. The different values between these two critical temperatures imply the inhomogeneity of the systems having phase separation, thus in agreement with the increased homogeneity with increasing $p$.