Effects of competing interactions on phase transition temperature in the Ising model

Abstract

This paper focuses on studying the influence of competitive interaction on the phase diagram in a disordered Ising model using the effective field method. The competitive interaction factor is controlled by two parameters, the competition probability p and the fluctuation D. We obtain a phase diagram divided into three distinct regions according to critical temperatures. Specifically, in the range 1 < D < 1.005 and D > 1.4, the system exhibits a single phase transition from ferromagnetic to paramagnetic states. In the range 1.005 ≤ D ≤ 1.4, two critical points t_c1 and t_c2 are formed corresponding to the AF – FM – PM phase transition sequence. Simultaneously, we observe that the shift of the phase transition temperature depends on the two model parameters (p, D), similar to the effect of doping concentration on the phase transition temperature in the doped manganese perovskites.