COLLOQUIUM: Magnetic imaging with point defects in diamond (Nov 2016)

Speaker: Jean-François ROCH, Université Paris-Saclay

Abstract:
The ability to quantitatively map magnetic field distributions is of crucial importance for fundamental studies ranging from materials science to biology, and for the development of new devices e.g. in spintronics. Recently it has been demonstrated that scanning magnetometry based on a single spin associated to an impurities hosted in a solid is an efficient technique which combines high sensitivity and nanoscale resolution. The sensing signal relies on the optical detection of the electron spin resonance associated with a single nitrogen-vacancy (NV) center in diamond attached to a AFM tip. The magnitude of the stray magnetic field above a magnetic sample can then be determined from the Zeeman shifts of the energy levels associated to this artificial atom in the solid state.

Extending this technique to a cryogenic environment will open the way to investigate many magnetic phenomena occuring in complex condensed matter systems, such as superconductivity or the magnetic properties of strongly correlated systems. I will present our recent realizations of a scanning magnetometer based on NV centers in a nanodiamond grafted at the apex of a AFM tip, and how they have been applied to the imaging of magnetic nanostructures. I will also describe how NV centers can be efficiently engineered by combining plasma-assisted diamond growth and nanoscale ion implantation.