The Impact of Internal Electric Fields on Accurate Diamond Magnetometry
Nitrogen-vacancy (NV) center spin ensembles are a promising platform for accurate vector magnetometry, as they offer measurements referenced to a spin Hamiltonian in an anisotropic crystal with native vector sensing capabilities. However, charged dopants within the diamond produce random internal electric fields (RIEFs) that shift NV spin-transition frequencies, and their impact on the accuracy of NV magnetometry has not been investigated. Here, we characterize RIEFs' effect on NV spin-transition spectra and propose an analytical fitting function to improve accuracy in their presence. We build a Monte Carlo RIEF model that reproduces the asymmetric lineshapes observed in experimental optically detected magnetic resonance (ODMR) spectra, and use it as a testbed to quantify RIEF-induced errors by simulating ODMR spectra including RIEFs and comparing reconstructed magnetic fields to the known model input. With standard analysis approaches, we observe systematic errors exceeding the g-factor uncertainty in fields below $\sim$ 5 mT, while the proposed fitting function reduces the error by nearly an order of magnitude. Our results demonstrate that RIEFs can play a significant role in the systematic error budget for NV magnetometry, and offer a path towards improved accuracy in NV quantum sensing.