High-Sensitivity Three-Axis Vector Magnetometry Using Electron Spin Ensembles in Single-Crystal Diamond

We demonstrate a three-axis vector magnetometer based on ensembles of negatively charged nitrogen vacancy centers in single-crystal diamond. A diamond with
$\text{C}_{3v}$
symmetry was used to establish the coordinate system for vector magnetic field sensing. We control the external static magnetic field with three-axis Helmholtz coils. Four pairs of magnetic resonance peaks were obtained, which were used to calculate the three Cartesian components of the magnetic field with sensitivity of
$\sim5\;\text{nT}/ \sqrt{\text{Hz}}$
for each Cartesian component, free of interaxis error. The magnetometer is suitable for single-chip manufacturing.