Extending spatial resolution and bandwidth of covariance magnetometry with nitrogen-vacancy centers

Recent discoveries in correlated materials motivate building next-generation sensors to directly characterize the correlation of the electromagnetic field produced by these materials. Although pairs of nitrogen-vacancy (NV) centers in diamond have been used to probe the two-point spatial and temporal correlator of the magnetic field, the state-of-the-art technique is restricted to lengthscale above diffraction limit and frequency range from kHz to a few MHz [1]. We extend this covariance magnetometry technique to below diffraction limit using inhomogeneity of the NVs’ local strain/electric field that results in different optical transitions for each NV [2]. We also perform different sensing modalities to probe correlation of magnetic field at 100s MHz-GHz range. Altogether, this realizes a new tool to study magnetic correlated phenomena in 2D magnets, such as magnons, domain wall dynamics, or critical fluctuations near phase transitions.

[1] Rovny et al., Science 378 (2022)

[2] Monge et al., Nat. Nanotechnol. 19, 264 (2024)