Random iron-nickel alloys: From first principles to dynamic spin fluctuation theory

TL;DR

This paper systematically studies the finite-temperature magnetic properties of disordered Fe-Ni alloys using first-principles calculations and compares different methods, highlighting the effectiveness of dynamic spin-fluctuation theory in matching experimental data.

Contribution

It introduces a comprehensive analysis combining electronic structure calculations with various approaches to predict magnetic properties, emphasizing the accuracy of dynamic spin-fluctuation theory.

Findings

Dynamic spin-fluctuation theory best fits experimental Curie temperatures.

Composition affects magnetic moments and density of states.

First-principles calculations elucidate electronic structure changes with alloy composition.

Abstract

We provide a systematic analysis of finite-temperature magnetic properties of random alloys Fe$_x$Ni$_{1-x}$ with the face-centered-cubic structure over a broad concentration range $x$. By means of the spin-polarized relativistic Korringa-Kohn-Rostoker method we calculate the electronic structure of disordered iron-nickel alloys and discuss how a composition change affects magnetic moments of Fe and Ni and the density of states. We investigate how the Curie temperature depends on Fe concentration using conventional approaches, such as mean-field approximation or Monte Carlo simulations, and dynamic spin-fluctuation theory. Being devised to account for spin fluctuations explicitly, the latter method shows the best fit to experimental results.