Phenomenology of chiral damping in noncentrosymmetric magnets

TL;DR

This paper introduces a phenomenological model for chiral magnetic damping in noncentrosymmetric magnets, highlighting its microscopic origins and effects on domain wall dynamics, with broad implications for magnetic texture control.

Contribution

It proposes a general form of magnetic damping tensor incorporating chiral effects and identifies microscopic mechanisms like spin pumping and Dzyaloshinskii-Moriya interactions responsible for this damping.

Findings

Chiral damping tensor includes a component linear in magnetization gradient.

Microscopic mechanisms such as spin pumping and Dzyaloshinskii-Moriya interactions can produce chiral damping.

Predictions show significant impact on domain wall motion in various magnetic regimes.

Abstract

A phenomenology of magnetic chiral damping is proposed in the context of magnetic materials lacking inversion symmetry breaking. We show that the magnetic damping tensor adopts a general form that accounts for a component linear in magnetization gradient in the form of Lifshitz invariants. We propose different microscopic mechanisms that can produce such a damping in ferromagnetic metals, among which spin pumping in the presence of anomalous Hall effect and an effective "$s$-$d$" Dzyaloshinskii-Moriya antisymmetric exchange. The implication of this chiral damping in terms of domain wall motion is investigated in the flow and creep regimes. These predictions have major importance in the context of field- and current-driven texture motion in noncentrosymmetric (ferro-, ferri-, antiferro-)magnets, not limited to metals.