Fast Scanning Nitrogen-Vacancy Magnetometry by Spectrum Demodulation
Pol Welter, B. Josteinsson, S. Josephy, Angela Wittmann, Andrea Morales, Gabriel Puebla‐Hellmann, Christian L. Degen
Abstract
We demonstrate a spectrum demodulation technique allowing for rapid imaging in scanning nitrogen-vacancy center magnetometry. Our method relies on a periodic excitation of the electron spin resonance by wide-band frequency sweeps at a kilohertz rate combined with a phase-locked detection of the photoluminescence signal. The technique is robust against changes in spectrum shape and photoluminescence intensity, and is readily extended by a frequency feedback to enable 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, such as for ferromagnets or ferrimagnets. We demonstrate our method by mapping stray fields above the model antiferromagnet $\ensuremath{\alpha}$-${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ (hematite) at pixel rates of up to $100\phantom{\rule{0.2em}{0ex}}\mathrm{Hz}$ and an image resolution exceeding one megapixel.