Magnon Kerr effect in a magnetic thin film strongly coupled to a microwave resonator

TL;DR

This paper demonstrates a tunable magnon Kerr effect in a strongly coupled yttrium iron garnet film and microwave resonator system, highlighting enhanced nonlinearity and potential for controlling magnon dynamics in hybrid systems.

Contribution

It introduces a scalable method to enhance Kerr nonlinearity in magnon-photon systems using shape anisotropy and strong coupling, with tunable Kerr effects.

Findings

Enhanced Kerr effect due to shape anisotropy

Continuous tunability of Kerr shift via magnetization orientation

Consistent modeling matching experimental Kerr coefficients

Abstract

Cavity magnonics investigates hybrid systems where magnons interact coherently with photons, providing a platform to harness light-matter interaction in magnetic materials. Progress in this field hinges on achieving stronger and tunable nonlinear effects, which are essential for controlling magnon dynamics and frequency conversion. Here, we demonstrate the magnon Kerr effect in an anisotropic magnonic system comprising a 200~nm-thick yttrium iron garnet film strongly coupled to a three-dimensional microwave resonator. The strong shape anisotropy significantly enhances the magnon Kerr effect compared to a sphere of equivalent volume, while the cavity enables sensitive probing of magnetization dynamics. We demonstrate continuous tunability of the magnitude and sign of the Kerr shift by controlling the static orientation of the magnetization. Input-output modeling of the magnon-photon interaction provides a consistent description of our system and Kerr coefficients matching the experimental results. Our findings demonstrate a scalable approach to enhancing Kerr anharmonicity in hybrid magnon-photon systems while preserving strong coupling.