Magnonic waveguide based on exchange-spring magnetic structure

TL;DR

This paper introduces a novel magnonic waveguide using exchange-spring magnetic structures, demonstrating localized spin-wave channels with high velocity and stability, promising advancements in energy-efficient magnonic devices.

Contribution

The study proposes and validates a new exchange-spring based magnetic waveguide for spin waves, offering improved localization and robustness over traditional domain wall methods.

Findings

Spin waves can be strongly localized in the exchange-spring channel.

The bound mode spin waves have a beamwidth smaller than 24nm.

The channel exhibits high group velocity and immunity to surroundings.

Abstract

We propose to use a soft/hard exchange-spring coupling bilayer magnetic structure to introduce a narrow channel for spin-wave propagation. We show by micromagnetic simulations that broad-band Damon-Eshbach geometry spin waves can be strongly localized into the channel and propagate effectively with a proper high group velocity. The beamwidth of the bound mode spin waves is almost independent from the frequency and is smaller than 24nm. For a low-frequency excitation, we further investigate the appearance of two other spin beams in the lateral of the channel. In contrast to a domain wall, the channel formed by exchange-spring coupling can be easier to realize in experimental scenarios and holds stronger immunity to surroundings. This work is expected to open new possibilities for energy-efficient spin-wave guiding as well as to help shape the field of beam magnonics.