Magnetization pumping and dynamics in a Dzyaloshinskii-Moriya magnet

TL;DR

This paper develops a phenomenological theory for magnetization dynamics in thin ferromagnetic layers with inversion asymmetry, highlighting the role of Dzyaloshinskii-Moriya interactions in magnon current-induced effects and potential spintronic applications.

Contribution

It introduces a generalized phenomenological framework linking Dzyaloshinskii-Moriya interactions to magnon-induced torques and forces in asymmetric ferromagnets.

Findings

Magnon current-induced torques are confirmed to originate from Dzyaloshinskii-Moriya interactions.

The theory applies to various systems including pyrochlore crystals and chiral magnets.

Potential applications include spin current generation and magnetization control.

Abstract

We formulate a phenomenological description of thin ferromagnetic layers with inversion asymmetry where the single-domain magnetic dynamics experiences magnon current-induced torques and leads to magnon-motive forces. We first construct a phenomenological theory based on irreversible thermodynamics, taking into account the symmetries of the system. Furthermore, we confirm that these effects originate from Dzyaloshinskii-Moriya interactions from the analysis based on the stochastic Landau-Lifshitz-Gilbert equation. Our phenomenological results generalize to a general form of Dzyaloshinskii-Moriya interactions and to other systems, such as pyrochlore crystals and chiral magnets. Possible applications include spin current generation, magnetization reversal and magnonic cooling.