Scanning superconducting quantum interference device on a tip for magnetic imaging of nanoscale phenomena

TL;DR

This paper introduces a novel scanning SQUID-on-tip microscope that achieves high magnetic sensitivity and nanoscale spatial resolution, enabling detailed imaging of magnetic phenomena in superconductors.

Contribution

The development of a SQUID-on-tip device integrated with a tuning fork for high-resolution, sensitive magnetic imaging at the nanoscale is a new approach in magnetic microscopy.

Findings

Achieved magnetic flux sensitivity of 1.8 μ_0/Hz^{1/2}.

Spatial resolution of approximately 200 nm demonstrated.

Successfully imaged vortex lattice and local AC magnetic response in superconductors.

Abstract

We describe a new type of scanning probe microscope based on a superconducting quantum interference device (SQUID) that resides on the apex of a sharp tip. The SQUID-on-tip is glued to a quartz tuning fork which allows scanning at a tip-sample separation of a few nm. The magnetic flux sensitivity of the SQUID is 1.8 {\mu}_0/Hz^{1/2} and the spatial resolution is about 200 nm, which can be further improved. This combination of high sensitivity, spatial resolution, bandwidth, and the very close proximity to the sample provides a powerful tool for study of dynamic magnetic phenomena on the nanoscale. The potential of the SQUID-on-tip microscope is demonstrated by imaging of the vortex lattice and of the local AC magnetic response in superconductors.