Chiral damping, chiral gyromagnetism and current-induced torques in textured one-dimensional Rashba ferromagnets

TL;DR

This paper explores how spin-orbit interaction and spatial asymmetry in one-dimensional Rashba ferromagnets lead to chiral effects in damping, gyromagnetism, and current-induced torques, aligning with recent experimental findings.

Contribution

It reveals the existence of chiral damping and gyromagnetism in Rashba ferromagnets and analyzes the impact of spin-orbit coupling on the gyromagnetic ratio.

Findings

Chiral damping differs between left- and right-handed domain walls.

The g factor exhibits chirality, indicating chiral gyromagnetism.

Scattering corrections influence the gyromagnetic ratio depending on spin-orbit coupling.

Abstract

We investigate Gilbert damping, spectroscopic gyromagnetic ratio and current-induced torques in the one-dimensional Rashba model with an additional noncollinear magnetic exchange field. We find that the Gilbert damping differs between left-handed and right-handed N\'eel-type magnetic domain walls due to the combination of spatial inversion asymmetry and spin-orbit interaction (SOI), consistent with recent experimental observations of chiral damping. Additionally, we find that also the spectroscopic $g$ factor differs between left-handed and right-handed N\'eel-type domain walls, which we call chiral gyromagnetism. We also investigate the gyromagnetic ratio in the Rashba model with collinear magnetization, where we find that scattering corrections to the $g$ factor vanish for zero SOI, become important for finite spin-orbit coupling, and tend to stabilize the gyromagnetic ratio close to its nonrelativistic value.