Nonreciprocal Bistability in Coupled Nonlinear Cavity Magnonics

Abstract

We propose a coupled nonlinear cavity-magnon system, consisting of two cavities, a second-order nonlinear element, and a yttrium-iron-garnet (YIG) sphere that supports Kerr magnons, to realize the sought-after highly tunable nonreciprocity. We first derive the critical condition for switching between reciprocity and nonreciprocity in the absence of magnon driving, and then numerically demonstrate that strong magnonic nonreciprocity can be achieved by violating this critical condition. When magnons are driven, we show that strong magnonic nonreciprocity can also be attained even within the critical condition. Compared to previous studies, the introduced nonlinear element not only relaxes the critical condition in both the weak and strong coupling regimes, but also offers an alternative means to tune magnonic nonreciprocity. Our work provides a promising avenue for realizing highly tunable nonreciprocal devices based on Kerr magnons.