# Observation of magnon cross-Kerr effect in cavity magnonics

**Authors:** Wei-Jiang Wu, Da Xu, Jie Qian, Jie Li, Yi-Pu Wang, J. Q. You  
**arXiv:** [2112.13807](https://arxiv.org/abs/2112.13807)  
**Date:** 2021-12-27  
**Summary page:** https://www.summarizepaper.com/en/paper/2112.13807v1/

## Key points

- In cavity magnonics, researchers have observed the magnon cross-Kerr effect.
- The effect involves a biased ferrimagnetic crystal with field inhomogeneity exhibiting both Kittel and higher-order magnetostatic modes.
- Experimental observations and theoretical analysis show a cross-Kerr-type interaction between these spin-wave modes.
- Researchers have integrated a multi-mode cavity magnonic system using one YIG sphere, demonstrating the unique interaction.
- This achievement paves the way for innovative cavity magnonic devices utilizing mode-mode interactions.
- The research contributes to understanding spin-wave computing and strong field interactions between nanomagnets and photonic cavities.

## Summary

In the field of cavity magnonics, researchers have observed a fascinating phenomenon known as the magnon cross-Kerr effect. This effect occurs when a biased ferrimagnetic crystal with field inhomogeneity exhibits both the familiar uniform-precession Kittel mode and a higher-order magnetostatic (HMS) mode. Through experimental observations and theoretical analysis, researchers have demonstrated a cross-Kerr-type interaction between these two spin-wave modes. This reciprocal relationship highlights an exchange interaction between the Kittel and HMS modes, resulting in the manifestation of the cross-Kerr effect in this system. By harnessing this unique interaction, researchers have successfully realized and integrated a multi-mode cavity magnonic system using just one yttrium iron garnet (YIG) sphere. This achievement opens up new avenues for studying magnetization dynamics and lays the groundwork for developing innovative cavity magnonic devices that utilize mode-mode interactions as an operational degree of freedom. Moreover, this research contributes to a broader understanding of spin-wave computing and highlights the potential for utilizing strong field interactions between nanomagnets and photonic cavities. The findings presented in this study add to the growing body of knowledge on spin waves and their applications in various technological domains.