An entropic simulational study of the spin-$1$ Baxter-Wu model in a crystal field

TL;DR

This study uses entropic sampling simulations to analyze the phase diagram and critical behavior of the spin-1 Baxter-Wu model in a crystal field, revealing a tetracritical line, a pentacritical point, and first-order transition features.

Contribution

It provides the first detailed phase diagram and critical point analysis of the spin-1 Baxter-Wu model in a crystal field using entropic sampling methods.

Findings

Identified the phase diagram with a tetracritical line and pentacritical point.

Located the critical temperature at approximately 0.98 and the critical crystal field at about 1.68.

Observed double-peak specific heat indicating first-order transitions.

Abstract

We investigate the critical behavior of the two-dimensional spin-$1$ Baxter-Wu model in a crystal field using entropic sampling simulations with the joint density of states. We obtain the temperature-crystal field phase diagram, which includes a tetracritical line ending at a pentacritical point. A finite-size scaling analysis of the maximum of the specific heat, while changing the crystal field anisotropy, is used to obtain a precise location of the pentacritical point. Our results give the critical temperature and crystal field as $T_{pc}=0.98030(10)$ and $D_{pc}=1.68288(62)$. We also detect that at the first-order region of the phase diagram, the specific heat exhibits a double peak structure as in the Schottky-like anomaly, which is associated with an order-disorder transition.