Inhomogeneous Gilbert damping from impurities and electron-electron interactions

TL;DR

This paper develops a unified theory for magnetic damping in itinerant electron ferromagnets, incorporating electron-electron interactions and disorder, revealing that interactions significantly enhance damping in weak ferromagnets.

Contribution

It introduces a comprehensive model linking Gilbert damping to spin conductivity, accounting for both disorder and electron-electron interactions, with a focus on weak ferromagnet regimes.

Findings

Gilbert damping coefficient expressed via spin conductivity.

Disorder and interaction effects are additive in damping.

Electron-electron interactions strongly enhance damping in weak ferromagnets.

Abstract

We present a unified theory of magnetic damping in itinerant electron ferromagnets at order $q^2$ including electron-electron interactions and disorder scattering. We show that the Gilbert damping coefficient can be expressed in terms of the spin conductivity, leading to a Matthiessen-type formula in which disorder and interaction contributions are additive. In a weak ferromagnet regime, electron-electron interactions lead to a strong enhancement of the Gilbert damping.