First-order transition features of the 3D bimodal random-field Ising model

TL;DR

This study uses advanced numerical methods to analyze the phase transition nature of the 3D bimodal random-field Ising model, revealing a continuous transition despite first-order-like features, challenging earlier mean-field predictions.

Contribution

It applies Wang-Landau and Lee entropic sampling techniques to clarify the transition type in the 3D bimodal RFIM, providing new insights into its critical behavior.

Findings

Transition appears continuous despite first-order-like features

Results contradict earlier mean-field tricritical point predictions

Numerical methods effectively characterize phase transition nature

Abstract

Two numerical strategies based on the Wang-Landau and Lee entropic sampling schemes are implemented to investigate the first-order transition features of the 3D bimodal ($\pm h$) random-field Ising model at the strong disorder regime. We consider simple cubic lattices with linear sizes in the range $L=4-32$ and simulate the system for two values of the disorder strength: $h=2$ and $h=2.25$. The nature of the transition is elucidated by applying the Lee-Kosterlitz free-energy barrier method. Our results indicate that, despite the strong first-order-like characteristics, the transition remains continuous, in disagreement with the early mean-field theory prediction of a tricritical point at high values of the random-field.