Self-aligned nanoscale SQUID on a tip

TL;DR

This paper presents a simple self-aligned fabrication method for creating nanoscale SQUIDs on a tip, enabling high-sensitivity magnetic imaging at the nanoscale with high field operation.

Contribution

The authors develop a novel self-aligned fabrication technique for nanoSQUIDs on a tip, achieving diameters down to 100 nm without lithography.

Findings

NanoSQUIDs with 100 nm diameter fabricated on a tip.

Flux sensitivity of 1.8×10^{-6} Φ_0/Hz^{1/2}.

Operates in magnetic fields up to 0.6 T.

Abstract

A nanometer-sized superconducting quantum interference device (nanoSQUID) is fabricated on the apex of a sharp quartz tip and integrated into a scanning SQUID microscope. A simple self-aligned fabrication method results in nanoSQUIDs with diameters down to 100 nm with no lithographic processing. An aluminum nanoSQUID with an effective area of 0.034 $\mu$m$^2$ displays flux sensitivity of 1.8$\cdot 10^{-6}$ $\Phi_0/\mathrm{Hz}^{1/2} and operates in fields as high as 0.6 T. With projected spin sensitivity of 65 $\mu_B/\mathrm{Hz}^{1/2}$ and high bandwidth, the SQUID on a tip is a highly promising probe for nanoscale magnetic imaging and spectroscopy.