Fabrication of all diamond scanning probes for nanoscale magnetometry

TL;DR

This paper presents an optimized method for fabricating all-diamond scanning probes with integrated NV centers, enabling high-sensitivity nanoscale magnetic imaging with improved spatial resolution.

Contribution

The authors develop a robust fabrication process for all-diamond scanning probes with integrated NV centers, suitable for high-resolution magnetic sensing in an atomic force microscope.

Findings

Probes achieve magnetic field sensitivity of approximately 50 nT/√Hz.

Successful imaging of magnetic stray fields from a single Ni nanorod.

Estimated NV-to-sample distance of a few tens of nanometers.

Abstract

The electronic spin of the nitrogen vacancy (NV) center in diamond forms an atomically sized, highly sensitive sensor for magnetic fields. To harness the full potential of individual NV centers for sensing with high sensitivity and nanoscale spatial resolution, NV centers have to be incorporated into scanning probe structures enabling controlled scanning in close proximity to the sample surface. Here, we present an optimized procedure to fabricate single-crystal, all-diamond scanning probes starting from commercially available diamond and show a highly efficient and robust approach for integrating these devices in a generic atomic force microscope. Our scanning probes consisting of a scanning nanopillar (200 nm diameter, $1-2\,\mu$m length) on a thin ($< 1\mu$m) cantilever structure, enable efficient light extraction from diamond in combination with a high magnetic field sensitivity ($\mathrm{\eta_{AC}}\approx50\pm20\,\mathrm{nT}/\sqrt{\mathrm{Hz}}$). As a first application of our scanning probes, we image the magnetic stray field of a single Ni nanorod. We show that this stray field can be approximated by a single dipole and estimate the NV-to-sample distance to a few tens of nanometer, which sets the achievable resolution of our scanning probes.