Improvement of a focused ion beam fabricated diamond pillar for scanning ensemble nitrogen-vacancy magnetometry probe using an ultrapure diamond

TL;DR

This paper presents a novel fabrication method for ultrapure diamond probes used in scanning NV magnetometry, achieving smaller probe diameters and improved magnetic sensing resolution.

Contribution

The authors develop a new fabrication process involving PVA and Pt/Pd capping with UV/ozone treatment to enhance diamond NV probes for nanoscale magnetic imaging.

Findings

Achieved 800 nm probe diameter with improved quality.

Demonstrated magnetic imaging with 200 nm resolution.

Measured NV spin coherence and magnetic sensitivity.

Abstract

Scanning diamond nitrogen-vacancy probe microscopy (SNVM) is an important tool for studying nanoscale condensed-matter phenomena. Ga$^+$-ion-focused-ion-beam (FIB) milling has been introduced as an available method for fabricating SNVM, while the probe diameter is limited to a few micrometers due to the Ga$^+$-induced damage. We report a method for improving the SNVM probes' quality, with an 800-nm diameter probe of ultrapure diamond, through polyvinyl alcohol and Pt/Pd capping, followed by UV/ozone exposure. The effectiveness of the method is confirmed by NVs' spin-coherence property measurements and magnetic domain structure imaging with a few-hundred-nanometer resolution and a 6.7 $\mu$T/Hz$^{1/2}$ sensitivity.