Kerr-Induced Synchronization of a Broadband Magnon-Phonon Hybrid Frequency Comb

Nonlinear magnonics has emerged as a prominent area of research, with a particular focus on on-chip Kerr nonlinearity. This effect is valuable both for its potential to manipulate magnon states and for its role in addressing the scalability challenges that magnonic devices face. In this Letter, we experimentally investigate a Kerr nonlinear magnomechanical system in a yttrium iron garnet thin-film device that supports magnon resonance coupled with multiple high-overtone bulk acoustic wave resonance modes. Notably, the enhanced Kerr nonlinearity resulting from the small mode volume enables clear bistability in the magnon mode at low excitation power. Additionally, we demonstrate the excitation of a magnon-phonon hybrid frequency comb using a single microwave tone and illustrate Kerr-induced synchronization of the frequency comb through externally injected reference microwaves, achieving over 130 comb teeth. Our findings provide a robust platform for the exploration of nonlinear magnonics and represent an advance in the development of on-chip frequency combs.