Three-Dimensional Imaging of Stray Magnetic Field with Nitrogen-Vacancy Centers in Diamond

Diamond with nitrogen-vacancy (NV) center is a material system with paramagnetic centers that are very sensitive to magnetic field perturbation. This characteristic makes diamond NV center an excellent sensor for high sensitivity and high-resolution magnetometry application. Thanks to the Zeeman effect, the splitting of its spin-1 degeneracy under magnetic field perturbation is responsible for its magnetic sensing ability. The energy level lifting of the NV spins is detectable through its spin-selective fluorescence. The vector of external magnetic field in the proximity of the NV spins can be inferred from the optically detected resonance spectrum. Here we present three-dimensional stray magnetic field vector imaging from a magnetic structure using an ensemble of NV spins in a (001) oriented diamond. The optically detected magnetic resonance spectrum is obtained by the continuous illumination of 532 nm laser and microwave frequency sweep over the resonance frequency of the electron spins. By interrogating NV spins around the magnetic structure, variations of resonance spectrum are acquired and local 3-dimensional vector magnetic field is recovered. The sensitivity of 2.5 µTHz^-1/2 is achieved from this diamond magnetometry with a spatial resolution of about 1 µm.