Micro-scale three-component quantum magnetometer based on nitrogen-vacancy color centers in diamond crystal

Signals of optically detected magnetic resonance (ODMR) have been studied in the scheme of a three-component quantum magnetometer based on nitrogen vacancy color centers in diamond crystal with a volume of $\sim$ 0.01 mm$^3$, mounted on the end of an optical fiber. A method for excitation of the ODMR signal is proposed that ensures the most reliable identification of the resonance lines at a minimum number of dead zones. A sensitivity to components of the field vector on a level of 76 nT $\cdot$ Hz$^{-1/2}$ is achieved, and it is shown that the shot-noise-limited sensitivity amounts to 6 nT $\cdot$ Hz$^{-1/2}$.