Scanning diamond NV center magnetometer probe fabricated by laser cutting and focused ion beam milling

The nitrogen-vacancy (NV) centers in diamond have been applied to scanning magnetometer probes combined with atomic force microscopy (AFM) to demonstrate nanometer-scale magnetic sensing and imaging. However, the scanning diamond NV center probe fabrication requires complicated processes including electron-beam lithography and photolithography. In this study, we introduce an alternative method to fabricate a scanning NV probe using laser cutting and focused ion beam (FIB) milling from a bulk diamond hosting an ensemble of NV centers. A few tens of micrometer-sized diamond pieces, cut by laser processing, were attached to the probe end of a quartz tuning-fork-based AFM. Then, it was fabricated into a few-micrometer-sized diamond NV center probe by using a donut-shaped milling pattern in the FIB processing to avoid damage to the diamond probe surface to degrade the NV⁻ charged state at the tip apex. By using a home-built scanning NV magnetometer probe microscopy setup, an optically detected magnetic resonance was measured to detect stray magnetic fields demonstrating the imaging of a magnetic structure of approximately 5-μm periodicity from a magnetic tape. This study offers a method with a higher degree of probe-shape control for scanning NV probe that will broaden its application capabilities.