Another Use for Diamond: Improved Scanning Probe Microscopy

Detection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1mT, and the corresponding field from a single proton is a few nano Teslas. A sensor able to detect such magnetic fields and image them with nanometer spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electron or nuclear spins in complex biological molecules and living cells, to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory. Present day sensitive solid-state magnetometers are generally based on macroscopic phenomena such as superconducting quantum interference devices or the Hall effect in semiconductors. Intriguing novel avenues such as magnetic force microscopy are also currently being explored. However, none of the existing technologies are capable of imaging individual electrons or nuclear spins under ambient conditions. Recently, using coherent manipulation of an individual electronic spin associated with a nitrogen-vacancy (NV) color center in diamond, ultra sensitive magnetic field detection with high spatial resolution has been achieved. Using an ultra-pure diamond tip carved out of a bulk piece of diamond, we have now been able to provide the first magnetic image of a single electron spin at room temperature. In this talk we will review some of the recent work on magnetic field sensing using NV centers in diamond as well as some of the potential applications this technique may provide.