Destruction of first-order phase transition in a random-field Ising model

TL;DR

This paper investigates how increasing randomness in a double-Gaussian magnetic field can eliminate first-order phase transitions in an infinite-range Ising model, providing insights into real magnetic systems.

Contribution

It introduces a more realistic double-Gaussian random field distribution and demonstrates its effect on destroying first-order phase transitions in the model.

Findings

First-order transitions are destroyed at higher field randomness.

Double-Gaussian distribution models real systems better than bimodal or single Gaussian.

Results are consistent with experimental observations in magnetic compounds.

Abstract

The phase transitions that occur in an infinite-range-interaction Ising ferromagnet in the presence of a double-Gaussian random magnetic field are analyzed. Such random fields are defined as a superposition of two Gaussian distributions, presenting the same width $\sigma$. Is is argued that this distribution is more appropriate for a theoretical description of real systems than its simpler particular cases, i.e., the bimodal ($\sigma=0$) and the single Gaussian distributions. It is shown that a low-temperature first-order phase transition may be destructed for increasing values of $\sigma$, similarly to what happens in the compound $Fe_{x}Mg_{1-x}Cl_{2}$, whose finite-temperature first-order phase transition is presumably destructed by an increase in the field randomness.