First-principles study of magnetic interactions in FeGe

TL;DR

This study employs first-principles calculations and real-space models to analyze the magnetic interactions in FeGe, highlighting the importance of RKKY coupling and accurately estimating its magnetic transition temperature.

Contribution

It introduces a comprehensive first-principles approach combining real-space Hamiltonian and micromagnetic models to study magnetic excitations in FeGe.

Findings

RKKY coupling is essential in FeGe's magnetic interactions.

Calculated transition temperature aligns well with experiments.

The approach effectively describes magnetic excitations in FeGe.

Abstract

We theoretically study the magnetic properties of iron germanium, known as one of canonical helimagnets. For this purpose we use the real-space spin Hamiltonian and micromagnetic model, derived in terms of Andersen's "local force theorem", to describe the low-lying magnetic excitations via spin-polarized Green's function, obtained from the first-principles calculations. The model was designed to numerically evaluate the spin stiffness constant in reciprocal space, in order for assessment of the contributing itinerant mechanisms. The calculated pairwise exchange interactions reveal the essentiality of Ruderman-Kittel-Kasuya-Yoshida coupling in FeGe. Thus provided mean-field estimation of magnetic transition temperature agrees good with the experimental measurement, underlining the necessity of the comprehensive real/reciprocal space-based approach for a proper description of magnetic excitations in FeGe.