Sensing Spin Wave Excitations by Spin Defects in Few-Layer Thick Hexagonal Boron Nitride

TL;DR

This paper demonstrates that boron vacancy spin defects in few-layer hexagonal boron nitride can optically detect spin waves in magnetic insulators like YIG, opening new avenues for quantum sensing and spin dynamics studies.

Contribution

It reports the first direct detection of spin waves in YIG using spin defects in layered hexagonal boron nitride via optically detected magnetic resonance.

Findings

Detection of ferromagnetic resonance and spin excitations via spin defects

Off-resonant dipole interactions mediated by multi-magnon scattering

Potential applications in quantum sensing and spin dynamic investigations

Abstract

Optically active spin defects in wide band-gap semiconductors serve as a local sensor of multiple degrees of freedom in a variety of "hard" and "soft" condensed matter systems. Taking advantage of the recent progress on quantum sensing using van der Waals (vdW) quantum materials, here we report direct measurements of spin waves excited in magnetic insulator Y3Fe5O12 (YIG) by boron vacancy $V_B^-$ spin defects contained in few-layer thick hexagonal boron nitride nanoflakes. We show that the ferromagnetic resonance and parametric spin excitations can be effectively detected by $V_B^-$ spin defects under various experimental conditions through optically detected magnetic resonance measurements. The off-resonant dipole interaction between YIG magnons and $V_B^-$ spin defects is mediated by multi-magnon scattering processes, which may find relevant applications in a range of emerging quantum sensing, computing, and metrology technologies. Our results also highlight the opportunities offered by quantum spin defects in layered two-dimensional vdW materials for investigating local spin dynamic behaviors in magnetic solid-state matters.