Magnetic sensing and imaging using nanodiamond NV center films and microwave integration into an STM coplanar waveguide stage

Abstract Spin-polarized scanning tunneling microscopy (SP-STM) enables access to the spin polarization of individual magnetic atoms but is inherently insensitive to magnetic fields. In contrast, nitrogen-vacancy (NV) centers in diamond provide highly sensitive magnetic-field detection through optically detected magnetic resonance (ODMR). Integrating ODMR-based magnetic-field sensing with SP-STM therefore offers a pathway to comprehensive magnetic characterization from the atomic scale to long-range fields. Here, we demonstrate that drop-cast nanodiamond (ND) films with an average particle size of ~100 nm deposited on glass substrates function as magnetic-field sensors for imaging magnetic domains under ambient conditions using a conventional ODMR setup. The random orientations of NV centers in the ND ensemble enable detection of magnetic fields with arbitrary directions without crystallographic alignment. Furthermore, we report progress toward integrating ODMR with SP-STM by developing an STM stage equipped with a coplanar waveguide, enabling reliable microwave delivery to the STM junction.