Magnon Kerr effect in a strongly coupled cavity-magnon system

TL;DR

This paper experimentally demonstrates the magnon Kerr effect in a cavity-magnon system, showing how strong coupling and magnon pumping cause frequency shifts, and provides an analytical model matching experimental data, opening avenues for nonlinear effects exploration.

Contribution

It presents the first experimental observation of the magnon Kerr effect in a cavity-magnon system with a theoretical model that matches the results.

Findings

Magnon Kerr effect causes measurable frequency shifts.

Analytical relation between drive power and magnon frequency shift.

Good agreement between theory and experiment for the Kittel mode.

Abstract

We experimentally demonstrate magnon Kerr effect in a cavity-magnon system, where magnons in a small yttrium iron garnet (YIG) sphere are strongly but dispersively coupled to the photons in a three-dimensional cavity. When the YIG sphere is pumped to generate considerable magnons, the Kerr effect yields a perceptible shift of the cavity's central frequency and more appreciable shifts of the magnon modes. We derive an analytical relation between the magnon frequency shift and the drive power for the uniformly magnetized YIG sphere and find that it agrees very well with the experimental results of the Kittel mode. Our study paves the way to explore nonlinear effects in the cavity-magnon system.