Effects of magnonic Kerr nonlinearity on magnon-polaritons with a soft-mode

TL;DR

This paper investigates how magnonic Kerr nonlinearity influences magnon-polaritons in ferromagnets, revealing chaotic behaviors, frequency combs, and a finite excitation gap in the soft-mode, especially under strong coupling conditions.

Contribution

It introduces an effective circuit model to analyze nonlinear effects on magnon-polaritons, including nonperturbative strong-coupling regimes and soft-mode excitation gaps.

Findings

Chaotic and frequency-comb behaviors emerge at mode crossing points.

Kerr nonlinearity induces a finite excitation gap in the soft-mode.

Nonperturbative strong-coupling regime behavior is characterized.

Abstract

We theoretically study the effects of magnonic Kerr nonlinearity on magnon-polaritons (MPs) with a soft-mode in easy-axis ferromagnets coupled to a microwave cavity. Using an effective circuit model capable of describing MPs up to the nonperturbative strong-coupling regime, we show that chaotic and frequency-comb-like behaviors of MPs emerge at the original modes crossing point. Furthermore, we demonstrate that the Kerr nonlinearity induces a finite excitation gap in the soft-mode, particularly in the strong-coupling regime.