Sub-millimeter propagation of antiferromagnetic magnons via magnon-photon coupling

TL;DR

This paper demonstrates that antiferromagnetic magnons can propagate over hundreds of micrometers via strong magnon-photon coupling in BiFeO₃, advancing the potential for optical control in magnonic and terahertz technologies.

Contribution

It provides the first direct observation of long-distance antiferromagnetic magnon propagation mediated by magnon-photon coupling using time-resolved imaging.

Findings

Antiferromagnetic magnons propagate over hundreds of micrometers.

Strong magnon-photon coupling observed in BiFeO₃.

Enhanced understanding of optical control in magnonic systems.

Abstract

For the realization of magnon-based current-free technologies, referred to as magnonics, all-optical control of magnons is an important technique for both fundamental research and practical applications. Magnon-polariton is a coupled state of magnon and photon in a magnetic medium, expected to exhibit magnon-like controllability and photon-like high-speed propagation. While recent studies have observed magnon-polaritons as modulation of incident terahertz waves, the influence of magnon-photon coupling on magnon propagation properties remains unexplored. This study aimed to observe the spatiotemporal dynamics of coherent magnon-polaritons through time-resolved imaging measurements. BiFeO$_3$ was selected as the sample due to its anticipated strong coupling between magnons and photons. The observed dynamics suggest that antiferromagnetic magnons can propagate over long distances, up to hundreds of micrometers, through strong coupling with photons. These results enhance our understanding of the optical control of magnonic systems, thereby paving the way for terahertz opto-magnonics.