Widefield Quantum Sensor for Vector Magnetic Field Imaging of Micromagnetic Structures

TL;DR

This paper demonstrates a practical widefield quantum sensor using NV centers in diamond for fast, vector-resolved magnetic field imaging of microstructures with high spatial resolution and sensitivity.

Contribution

It introduces a camera-compatible pulsed NV magnetometry protocol on a standard microscope for vector magnetic field imaging of microfabricated structures.

Findings

Achieved 0.52 μm spatial resolution over 83 μm field of view.

Peak sensitivity of approximately 828 nT/Hz^{1/2}.

Imaging completed within a few minutes.

Abstract

Many spintronic, magnetic-memory, and neuromorphic devices rely on spatially varying magnetic fields. Quantitatively imaging these fields with full vector information over extended areas remains a major challenge. Existing probes either offer nanoscale resolution at the cost of slow scanning, or widefield imaging with limited vector sensitivity or material constraints. Quantum sensing with nitrogen-vacancy (NV) centers in diamond promises to bridge this gap, but a practical camera-based vector magnetometry implementation on relevant microstructures has not been demonstrated. Here we adapt a commercial widefield microscope to implement a camera-compatible pulsed optically detected magnetic resonance protocol to reconstruct stray-field vectors from microscale devices. By resolving the Zeeman shifts of the four NV orientations, we reconstruct the stray-field vector generated by microfabricated permalloy structures that host multiple stable remanent states. Our implementation achieves a spatial resolution of $\approx 0.52 ~\mu\mathrm{m}$ across an $83~\mu\mathrm{m} \times 83~\mu\mathrm{m}$ field of view and a peak sensitivity of $ (828 \pm 142)~\mathrm{nT\,Hz^{-1}}$, with acquisition times of only a few minutes. These results establish pulsed widefield NV magnetometry on standard microscopes as a practical and scalable tool for routine vector-resolved imaging of complex magnetic devices.