Nonreciprocal multimode and indirect couplings in cavity magnonics

Abstract

We investigate magnon-photon couplings by employing a small magnet within an irregular resonant cavity, which leads to a desirable nonreciprocity with a big isolation ratio. Moreover, the higher-order couplings between the spin wave modes and the polarized photon modes also exhibit the nonreciprocity. These couplings between polarized photon and spin waves could be regarded as a multimode hybridization mediated by cavity photons. We also derive a coupling matrix to predict the characteristics of this kind of indirect coupling. The existence of indirect couplings broadens the field range of the nonreciprocity of the system. The achieved nonreciprocal multimode magnon-photon couplings in a single system offer a feasible method to improve the signal transmission quality.