Spin Hall phenomenology of magnetic dynamics

TL;DR

This paper develops a phenomenological framework to analyze spin-orbit interaction effects on magnetic dynamics in ferromagnetic films with conductors, applicable to various models and experimental scenarios.

Contribution

It introduces a comprehensive phenomenological approach for understanding current-induced magnetic dynamics and charge pumping, avoiding detailed microscopic modeling.

Findings

Framework applicable to Rashba and Dirac electron gases

Analysis of magnetoresistance and Gilbert damping effects

Insights into spin-orbit interactions and magnetic textures

Abstract

We study the role of spin-orbit interactions in the coupled magnetoelectric dynamics of a ferromagnetic film coated with an electrical conductor. While the main thrust of this work is phenomenological, several popular simple models are considered microscopically in some detail, including Rashba and Dirac two-dimensional electron gases coupled to a magnetic insulator, as well as a diffusive spin Hall system. We focus on the long-wavelength magnetic dynamics that experiences current-induced torques and produces fictitious electromotive forces. Our phenomenology provides a suitable framework for analyzing experiments on current-induced magnetic dynamics and reciprocal charge pumping, including the effects of magnetoresistance and Gilbert-damping anisotropies, without a need to resort to any microscopic considerations or modeling. Finally, some remarks are made regarding the interplay of spin-orbit interactions and magnetic textures.