On-Chip Coherent Transduction between Magnons and Acoustic Phonons in Cavity Magnomechanics

Coherent control of collective spin excitations (magnons) with acoustic phonons is a key technology for future hybrid spintronics devices. Surface acoustic waves (SAWs), owing to their high frequency, short wavelength, and low radiation loss, could provide an appropriate platform for integrating the devices on a chip. However, the tiny coupling efficiency in previous experiments using traveling SAWs limits the availability of this prospect. We report a planar cavity magnomechanical system, where standing acoustic waves (i.e., a SAW cavity) enhance the spatial and spectral power density to implement magnified magnon-phonon coupling. Excitation of spin-wave resonance involves significant acoustic power absorption approaching 90%, whereas the collective spin motion exerts hybridization force on the cavity dynamics, leading to coupling cooperativity exceeding unity at room temperature in such a chip-scale device. The cavity magnomechanical system paves the way to the coherent acoustic control of magnons and the development of alternative spin-acoustic technologies for classical and quantum applications.