Scanning nitrogen-vacancy magnetometry down to 350mK

TL;DR

This paper demonstrates the implementation of a scanning NV magnetometer at 350mK, enabling non-invasive magnetic imaging of superconducting vortices at sub-Kelvin temperatures.

Contribution

It introduces a method for scanning NV magnetometry in a dilution refrigerator, achieving low temperatures and imaging superconducting vortices.

Findings

Achieved a base temperature of 350 mK in the setup.

Successfully imaged superconducting vortices in aluminum microstructures.

Measured magnetic sensitivity of approximately 3 μT/√Hz.

Abstract

We report on the implementation of a scanning nitrogen-vacancy (NV) magnetometer in a dry dilution refrigerator. Using pulsed optically detected magnetic resonance combined with efficient microwave delivery through a co-planar waveguide, we reach a base temperature of 350 mK, limited by experimental heat load and thermalization of the probe. We demonstrate scanning NV magnetometry by imaging superconducting vortices in a 50-nm-thin aluminum microstructure. The sensitivity of our measurements is approximately 3 {\mu}T per square root Hz. Our work demonstrates the feasibility for performing non-invasive magnetic field imaging with scanning NV centers at sub-Kelvin temperatures.