Magnetometry techniques based on nitrogen-vacancy (NV) defects in diamond have received much attention of late as a means to probe nanoscale magnetic environments. The sensitivity of a single NV magnetometer is primarily determined by the transverse spin-relaxation time, $T_2$. Current approaches to improving the sensitivity employ crystals with a high NV density at the cost of spatial resolution or extend $T_2$ via the manufacture of novel isotopically pure diamond crystals. We adopt a complementary approach in which optimal dynamic decoupling techniques extend coherence times out to the self-correlation time of the spin bath. This suggests single spin, room-temperature magnetometer sensitivities as low as $5\text{pT}{\text{Hz}}^{-1/2}$ may be possible with current technology.

• Received 19 March 2010

DOI:https://doi.org/10.1103/PhysRevB.82.045208