A scanning NV center magnetometry probe fabricated by a focused ion beam*

Utilizing the NV (Nitrogen-Vacancy) center in diamond as a scanning magnetometry probe is gaining much attention owing to its potential for high magnetic field sensitivity with nanometer-scale spatial resolution. The scanning NV magnetometry probe has been fabricated by using complicated methods such as electron beam lithography. We introduce an alternative method for this by using laser cutting and forcused ion beam (FIB) milling. By using laser cutting, a thin diamond bulk sample, which has NVs near-surface can be flexibly fabricated into blocks of several tenths of micrometers size. Successively, with a donut-shaped FIB milling pattern, avoiding the damage of NV states by Ga⁺ ion in FIB fabrication at the probe center position, a diamond pillar probe hosting NVs near the surface with a diameter of about 1 – 2 micrometer was fabricated. With this probe, a micrometer scale magnetic structure imaging from a magnetic tape was demonstrated via stray magnetic field detection. For improvement of the NV probe's magnetic sensing ability, reducing the diameter of the probe to less than one hundred nanometers, without NVs’ damage is required. For this, protection of NV layers at the probe by a PtPd metal film deposition during FIB fabrication was examined.