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.
@article{arxiv.1712.03392,
title = {Magnonic waveguide based on exchange-spring magnetic structure},
author = {Lixiang Wang and Leisen Gao and Lichuan Jin and Yulong Liao and Tianlong Wen and Xiaoli Tang and Huaiwu Zhang and Zhiyong Zhong},
journal= {arXiv preprint arXiv:1712.03392},
year = {2017}
}