Direct measurement of foldover in cavity magnon-polariton systems

Abstract

An approach to directly measure the nonlinear foldover effect for cavity magnon polaritons is demonstrated by placing a nonlinear medium (yttrium iron garnet) into a Fabry-Perot-like microwave cavity. The resulting bistability features can exhibit clockwise, counterclockwise, and butterflylike hysteresis loops and are solely dependent on the relative weight of the magnonlike and photonlike components. In addition to accurately describing our experimental observations, our model also allows us to calculate the crucial system conditions required to produce photonlike foldover effects. Though the photon subsystem has no nonlinear components of its own, these photonlike foldover effects are produced through light-matter interactions with a nonlinear magnetic subsystem. Our model's description of these nonlinear light-matter interactions and their effects is not limited to ferromagnetic systems and should be generally applicable to other coherent coupled systems.