Magnetic Measurement of SPIONs using NVs in Diamond*

Superparamagnetic iron oxide nanoparticles (SPIONs) have numerous biological, magnetic, and chemical applications. Their nontoxicity and functionalizability supports medical applications as temporally and spatially controlled nanovectors for drug delivery, markers for enhanced MRI sensitivity, and for externally controlled hyperthermia in tumors. While bulk magnetic properties of SPIONs have been the subject of numerous studies, the magnetic properties of single SPIONs aren't well understood. Nitrogen vacancy defects in diamond are particularly suitable for characterizing isolated nanoparticles due to their extreme sensitivity to local magnetic fields. We characterize the magnetic properties of SPIONs of varying size and density, deposited on the surface of NV implanted diamond.