  Cavity magnonics is an emerging research area focusing on the coupling
between magnons and photons. Despite its great potential for coherent
information processing, it has been long restricted by the narrow interaction
bandwidth. In this work, we theoretically propose and experimentally
demonstrate a novel approach to achieve broadband photon-magnon coupling by
adopting slow waves on engineered microwave waveguides. To the best of our
knowledge, this is the first time that slow wave is combined with hybrid
magnonics. Its unique properties promise great potentials for both fundamental
research and practical applications, for instance, by deepening our
understanding of the light-matter interaction in the slow wave regime and
providing high-efficiency spin wave transducers. The device concept can be
extended to other systems such as optomagnonics and magnomechanics, opening up
new directions for hybrid magnonics.
