Recent developments in magnetic field sensing with negatively charged nitrogen-vacancy centers (NV) in diamond employ magnetic-field (MF) dependent features in the photoluminescence (PL) and eliminate the need for microwaves (MW). Here, we study two approaches towards improving the magnetometric sensitivity using the ground-state level anti-crossing (GSLAC) feature of the NV center at a background MF of 102.4,mT. Following the first approach, we investigate the feature parameters for precise alignment in a dilute diamond sample; the second approach extends the sensing protocol into absorption via detection of the GSLAC in the diamond transmission of a 1042,nm laser beam. This leads to an increase of GSLAC contrast and results in a magnetometer with a sensitivity of 0.45,nT/$sqrt{text{Hz}}$ and a photon shot-noise limited sensitivity of 12.2 pT/$sqrt{rm{Hz}}$.
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