Bistability in dissipatively coupled cavity magnonics

TL;DR

This paper investigates nonlinear bistable behaviors in a dissipatively coupled cavity magnonic system with YIG, revealing reduced threshold for bistability and potential applications in low-power devices and non-Hermitian physics exploration.

Contribution

It demonstrates the observation of bistability in a dissipatively coupled cavity magnonic system and models it using a coupled oscillator framework, highlighting the suppression of magnon damping.

Findings

Bistability observed as hysteresis loops with different shapes.

Dissipative coupling reduces the threshold for magnon Kerr bistability.

Experimental results align with a Duffing oscillator coupled to a harmonic oscillator model.

Abstract

Dissipative coupling of resonators arising from their cooperative dampings to a common reservoir induces intriguingly new physics such as energy level attraction. In this study, we report the nonlinear properties in a dissipatively coupled cavity magnonic system. A magnetic material YIG (yttrium iron garnet) is placed at the magnetic field node of a Fabry-Perot-like microwave cavity such that the magnons and cavity photons are dissipatively coupled. Under high power excitation, a nonlinear effect is observed in the transmission spectra, showing bistable behaviors. The observed bistabilities are manifested as clockwise, counterclockwise, and butterfly-like hysteresis loops with different frequency detuning. The experimental results are well explained as a Duffing oscillator dissipatively coupled with a harmonic one and the required trigger condition for bistability could be determined quantitatively by the coupled oscillator model. Our results demonstrate that the magnon damping has been suppressed by the dissipative interaction, which thereby reduces the threshold for conventional magnon Kerr bistability. This work sheds light upon potential applications in developing low power nonlinearity devices, enhanced anharmonicity sensors and for exploring the non-Hermitian physics of cavity magnonics in the nonlinear regime.