Probing metal thin films with NV-centers in diamond*

Atomic-sized color centers in diamond (NV centers) have demonstrated nanoscale sensing of various properties such as electric and magnetic fields, strain, and temperature. Shallowly implanted NV center ensembles are inherently sensitive to magnetic resonance signals from molecules at the diamond surface. Recently they have been successfully applied to investigate the formation of self-assembled monolayers on an aluminum oxide layer deposited on the diamond surface. A novel research direction is the investigation of thin metal films on top of the diamond surface and surface processes on these. Metal surfaces play a key role in catalysis and electrochemistry, and a better understanding can foster new development with far-reaching implications. Metallic surfaces, however, pose severe challenges to NV-based surface measurements due to interactions between the metal and the NV centers, leading to a drastic decrease in the luminescence (quenching) of the NV centers – the primary source to read out the NV signal. We have investigated these effects on several diamond chips with NV centers of a variety of different depths to find optimal parameters regarding the sensitivity of these quantum sensors with respect to metal surfaces. This study presents an NV ensemble with optimized parameters for magnetic resonance spectroscopy on thin metal films.