Numerical study of the critical exponents and magnetic properties of the random field mixed spin

By exploiting the Monte Carlo simulation technique, based on the Metropolis algorithm, we have investigated the mixed spin-1/2 and spin-1 Ising model in a simple cubic structure, with random magnetic field. This method was used to study phase diagrams, thermal variation of magnetizations and magnetic susceptibility, when the random field is bimodally and trimodally distribution. The results demonstrate that the system exhibits multiple qualitatively distinct types of phase diagram, depending on the values of the reduced random magnetic field H/J and the probability of distribution of this field p. When the values of the distribution probability and the reduced random field are insufficiently large, tricritical behavior manifests. Furthermore, the disorder of the system becomes difficult when the probability p is important in contrast to the random field, and the simple Ising system is found for H/J=0 and p=1. The values of the critical exponents associated with spontaneous magnetization and magnetic susceptibility have been well estimated and are very close to the universal values of the three-dimensional Ising model: β≈0.32218 and γ≈1.28182.