Optimization Of The Coherence Properties Of Diamond Samples With An Intermediate Concentration Of Nv Centers

The sensitivity of the nitrogen-vacancy (NV) color centers in diamond-based magnetometers strongly depends on the number of NV centers involved in the measurement. Unfortunately, an increasing concentration of NV centers leads to a decrease in their dephasing and coherence times if the nitrogen content exceeds a certain threshold level (approximately 10(17) cm(-3) or 0.6 ppm). Here, we demonstrate that this increased dephasing can be efficiently compensated for by optimizing the electron irradiation dose in postprocessing procedures in the vicinity of the threshold concentration, thus extending the range of possible useful concentrations of NV centers in diamonds with a natural carbon content.