Scaling and universality in the phase diagram of the 2D Blume-Capel model

TL;DR

This paper investigates the phase diagram of the 2D Blume-Capel model using advanced Monte Carlo simulations to explore transition types, finite-size effects, and universality, especially near critical points.

Contribution

It introduces a high-precision simulation approach combining multicanonical and hybrid algorithms to analyze the model's correlation length and universality in detail.

Findings

Correlation length scaling matches Ising universality class

First-time analysis of correlation length in the model

High-precision results near phase transition boundaries

Abstract

We review the pertinent features of the phase diagram of the zero-field Blume-Capel model, focusing on the aspects of transition order, finite-size scaling and universality. In particular, we employ a range of Monte Carlo simulation methods to study the 2D spin-1 Blume-Capel model on the square lattice to investigate the behavior in the vicinity of the first-order and second-order regimes of the ferromagnet-paramagnet phase boundary, respectively. To achieve high-precision results, we utilize a combination of (i) a parallel version of the multicanonical algorithm and (ii) a hybrid updating scheme combining Metropolis and generalized Wolff cluster moves. These techniques are combined to study for the first time the correlation length of the model, using its scaling in the regime of second-order transitions to illustrate universality through the observed identity of the limiting value of $\xi/L$ with the exactly known result for the Ising universality class.