Phase diagram of the random-field Ising model with a trimodal distribution

Abstract

The random-field Ising model, with a trimodal distribution (sum of three \ensuremath{\delta} functions), is studied within the mean-field approximation. The averaged free energy and order parameter are numerically analyzed in detail, and through the Landau expansion, to construct the complete phase diagram in the parameter space of the system. A line of tricritical points, ending at a vestigial tricritical point, is obtained, a result also suggested recently by Mattis. Some new features of the phase diagram are also reported.