Broadband magnomechanics enabled by magnon–spoof plasmon hybridization

Cavity magnomechanics is an important hybrid magnonic platform that focuses on the coherent interaction between magnons and phonons. The resulting magnon polarons inherit the intrinsic properties of both magnons and phonons, combining their individual advantages and enabling new physics and functionalities. However, in previous demonstrations the magnon-phonon coupling either had limited bandwidth or could not be efficiently accessed. In this work, we show that by the use of the slow-wave hybrid magnonics configuration based on spoof surface plasmon polaritons (SSPPs), the coherent magnon-phonon interaction can be efficiently observed over a frequency range greater than 7 GHz on an yttrium iron garnet thin film device. In particular, the capability of the SSPPs in exciting short-wavelength magnons reveals a novel size effect when the magnons are coupled with high-overtone bulk acoustic resonances. Our work paves the way towards novel magnomechanical devices.