Curved magnonic waveguides based on domain walls

TL;DR

This paper demonstrates theoretically and through simulations that domain walls in ultrathin ferromagnetic films can guide spin waves effectively in curved geometries with minimal loss, showing potential for magnonic device applications.

Contribution

It introduces a novel method for guiding spin waves along curved domain walls, including nonreciprocal effects in Neel-type walls with Dzyaloshinskii-Moriya interaction.

Findings

Spin waves can be guided in curved domain wall channels with low scattering.

Localized spin wave modes exist within the frequency gap of bulk modes.

Group velocities can exceed 1 km/s in certain conditions.

Abstract

The channeling of spin waves with domain walls in ultrathin ferromagnetic films is demonstrated theoretically and through micromagnetics simulations. It is shown that propagating excitations localized to the wall, which appear in the frequency gap of bulk spin wave modes, can be guided effectively in curved geometries and can propagate in close proximity to other channels with no perceptible scattering or loss in coherence. For N\'eel-type walls arising from an interfacial Dzyaloshinskii-Moriya interaction, the channeling is strongly nonreciprocal and group velocities can exceed 1 km/s in the long wavelength limit for certain propagation directions.