Custom built atomic force microscope for nitrogen-vacancy diamond magnetometry

Abstract

The nitrogen-vacancy (N-V) center in diamonds have the potential to be an ultra-sensitive magnetic field sensor that is capable of detecting single spins. Implementing this sensor for general and nontransparent samples is not trivial. For N-V centers to be a useful probe, a way of positioning the NV center with nanometer accuracy while simultaneously measuring its fluorescence is needed. Here, a method of using N-V centers as magnetometer probes by combining this sensor with Atomic Force Microscopy (AFM) is described. A custom AFM was built that allows optical monitoring of the cantilever tip and collection of fluorescence with a high-NA objective from the same side. The AFM has a large open bottom and top and thus provides dual optical access. The motion of the cantilever is measured by optical beam deflection so that a wide range of commercial cantilevers can be used. The AFM and the confocal microscope objective can be locked in position while a piezoelectric stage allows raster scanning of the substrate.