We demonstrate a spectrum demodulation technique for greatly speeding up the data acquisition rate in scanning nitrogen-vacancy center magnetometry. Our method relies on a periodic excitation of the electron spin resonance by fast, wide-band frequency sweeps combined with a phase-locked detection of the photo-luminescence signal. The method can be extended by a frequency feedback to realize real-time tracking of the spin resonance. Fast scanning magnetometry is especially useful for samples where the signal dynamic range is large, of order millitesla, like for ferro- or ferrimagnets. We demonstrate our method by mapping stray fields above the model antiferromagnet α-Fe2O3 (hematite) at pixel rates of up to 100\,Hz and an image resolution exceeding one megapixel.
@article{arxiv.2205.06579,
title = {Fast scanning nitrogen-vacancy magnetometry by spectrum demodulation},
author = {P. Welter and B. A. Josteinsson and S. Josephy and A. Wittmann and A. Morales and G. Puebla-Hellmann and C. L. Degen},
journal= {arXiv preprint arXiv:2205.06579},
year = {2022}
}