Cluster size effects in the magnetic properties of Fe$_p$-Al$_{q=1-p}$ alloys

TL;DR

This study models the magnetic properties of Fe-Al alloys using a spin-1/2 Ising model with Monte Carlo simulations, revealing how cluster size influences critical temperature and aligning well with experimental data.

Contribution

It introduces a detailed Ising model incorporating cluster-dependent superexchange interactions and employs advanced simulation techniques to match experimental critical temperatures.

Findings

Good agreement with experimental critical temperatures

Cluster size significantly affects magnetic interactions

Monte Carlo methods effectively model alloy behavior

Abstract

A spin-1/2 Ising model, defined in the body centered cubic lattice, is used to describe some of the thermodynamic properties of Fe$_p$-Al$_q$ alloys, with $p+q=1$. The model assumes, besides the nearest-neighbor exchange coupling, the existence of further next-nearest-neighbor superexchange interactions, where the latter ones depend on the aluminum atoms cluster size. The Ising system so considered is studied by employing Monte Carlo simulations, using a hybrid algorithm consisting of one single-spin Metropolis move together with one single-cluster Wolff algorithm allied, in addition, with single histograms procedures and finite-size scaling techniques. Quite good fits to the experimental results of the ordering critical temperature, as a function of Al concentration in the range $0\le q<0.7$, are obtained and compared to more recent theoretical approaches done on the same alloys.