Magnons in real materials from density-functional theory

TL;DR

This paper introduces a computational method combining density-functional theory and Berry curvature calculations to accurately simulate magnon excitations in real materials, demonstrated on iron with excellent experimental agreement.

Contribution

The authors develop a novel approach to calculate magnon spectra from first principles using constrained density-functional theory and Berry curvature, enabling realistic material predictions.

Findings

Accurate magnon spectra for iron match experimental data.

New computational technique based on constrained DFT and Berry curvature.

Efficiently decouples spin and charge excitations in many-electron systems.

Abstract

We present an implementation of the adiabatic spin-wave dynamics of Niu and Kleinman. This technique allows to decouple the spin and charge excitations of a many-electron system using a generalization of the adiabatic approximation. The only input for the spin-wave equations of motion are the energies and Berry curvatures of many-electron states describing frozen spin spirals. The latter are computed using a newly developed technique based on constrained density-functional theory, within the local spin density approximation and the pseudo-potential plane-wave method. Calculations for iron show an excellent agreement with experiments.