Quantum Sensing of Broadband Spin Dynamics and Magnon Transport in Antiferromagnets

TL;DR

This paper demonstrates optically detecting antiferromagnetic resonance and magnon transport in layered van der Waals antiferromagnets up to 24 GHz, revealing new capabilities of quantum spin sensors for high-frequency magnetic phenomena.

Contribution

First experimental demonstration of optically detected AFMR in layered van der Waals antiferromagnets and analysis of magnon transport using quantum spin sensors.

Findings

AFMR spectroscopy characterizes exchange fields and anisotropies.

Magnon transport observed over tens of micrometers.

Detection efficiency increases with frequency.

Abstract

Optical detection of magnetic resonance using quantum spin sensors (QSS) provides a spatially local and sensitive technique to probe spin dynamics in magnets. However, its utility as a probe of antiferromagnetic resonance (AFMR) remains an open question. We report the first experimental demonstration of optically detected AFMR in layered van der Waals antiferromagnets (AF) up to frequencies of 24 GHz. We leverage QSS spin relaxation due to low-frequency magnetic field fluctuations arising from collective dynamics of magnons excited by the uniform AFMR mode. First, through AFMR spectroscopy we characterize the intrinsic exchange fields and magnetic anisotropies of the AF. Second, using the localized sensitivity of the QSS we demonstrate magnon transport over tens of micrometers. Finally, we find that optical detection efficiency increases with increasing frequency. This showcases the dual capabilities of QSS as detectors of high frequency magnetization dynamics and magnon transport, paving the way for understanding and controlling the magnetism of antiferromagnets.