Finite-temperature second-order perturbation analysis of magnetocrystalline anisotropy energy of L10-type ordered alloys

TL;DR

This paper introduces a finite-temperature second-order perturbation method with spin-orbit coupling to analyze the temperature-dependent magnetocrystalline anisotropy energy in alloys, revealing limitations of existing spin models.

Contribution

The authors develop a novel perturbation approach that accurately captures temperature effects on MAE and identifies key atomic sites influencing magnetic anisotropy in alloys.

Findings

Successfully reproduces previous results using the force theorem.

Identifies key sites responsible for MAE behavior in FePt, MnAl, and FeNi.

Highlights the inadequacy of spin models for itinerant magnets.

Abstract

We present a novel finite-temperature second-order perturbation method incorporating spin-orbit coupling to investigate the temperature-dependent site-resolved contributions to the magnetocrystalline anisotropy energy (MAE), specifically K1(T), in FePt, MnAl, and FeNi alloys. Our developed method successfully reproduces the results obtained using the force theorem from our previous work. By employing this method, we identify the key sites responsible for the distinctive behaviors of MAE in these alloys, shedding light on the inadequacy of the spin model in capturing the temperature dependence of MAE in itinerant magnets. Moreover, we explore the lattice expansion effect on the temperature dependence of on-site contributions to K1(T) in FeNi. Our results not only provide insights into the limitations of the spin model in explaining the temperature dependence of MAE in itinerant ferromagnets but also highlight the need for further investigations. These findings contribute to a deeper understanding of the complex nature of MAE in itinerant magnetic systems.