Spin Wave Eigenmodes of Dzyaloshinskii Domain Walls

TL;DR

This paper develops a theoretical model for the spin wave eigenmodes in Dzyaloshinskii domain walls, revealing their scattering properties, energy gaps, and implications for domain wall dynamics in ultrathin ferromagnets.

Contribution

It introduces a continuum theory for spin wave modes in Dzyaloshinskii domain walls, highlighting differences from Bloch walls and analyzing their scattering and band structure effects.

Findings

Spin wave potential in Dzyaloshinskii walls is not reflectionless.

A gap due to Dzyaloshinskii interaction affects spin wave behavior.

Finite scattering cross-section influences spin wave and domain wall interactions.

Abstract

A theory for the spin wave eigenmodes of a Dzyaloshinskii domain wall is presented. These walls are N\'eel-type domain walls that can appear in perpendicularly-magnetized ultrathin ferromagnets in the presence of a sizeable Dzyaloshinskii-Moriya interaction. The mode frequencies for spin waves propagating parallel and perpendicular to the domain wall are computed using a continuum approximation. In contrast to Bloch-type walls, it is found that the spin wave potential associated with Dzyaloshinskii domain walls is not reflectionless, which leads to a finite scattering cross-section for interactions between spin waves and domain walls. A gap produced by the Dzyaloshinskii interaction emerges, and consequences for spin wave driven domain wall motion and band structures arising from periodic wall arrays are discussed.