Multicritical Behavior in a Random-Field Ising Model under a Continuous-Field Probability Distribution

A random-field Ising model that is capable of exhibiting a rich variety of multicritical phenomena, as well as a smearing of such behavior, is investigated. The model consists of an infinite-range-interaction Ising ferromagnet in the presence of a triple-Gaussian random magnetic field, which is defined as a superposition of three Gaussian distributions with the same width $\sigma$, centered at H=0 and $H=\pm H_0$, with probabilities $p$ and $(1-p)\mathrm{/}2$, respectively. Such a distribution is very general and recovers as limiting cases, the trimodal, bimodal, and Gaussian probability distributions.