# 3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materials

## TL;DR

This paper introduces a novel 3D nano-bridge SQUID susceptometer for high-resolution magnetic imaging of quantum materials, demonstrating its capabilities in scanning magnetometry and susceptibility measurements.

## Contribution

The paper presents a new design and fabrication of 3D Nb nano-bridge SQUIDs with integrated pickup loops for enhanced magnetic imaging of quantum materials.

## Key findings

- Flux noise around 1 μΦ₀/√Hz at 100 Hz
- Pickup loop diameter of 1 μm
- Successful demonstration of scanning magnetometry and susceptometry

## Abstract

We designed and fabricated a new type of superconducting quantum interference device (SQUID) susceptometers for magnetic imaging of quantum materials. The 2-junction SQUID sensors employ 3D Nb nano-bridges fabricated using electron beam lithography. The two counter-wound balanced pickup loops of the SQUID enable gradiometric measurement and they are surrounded by a one-turn field coil for susceptibility measurements. The smallest pickup loop of the SQUIDs were 1 ${\mu}m$ in diameter and the flux noise was around 1 $\mu{\Phi}_0/\sqrt{Hz}$ at 100 Hz. We demonstrate scanning magnetometry, susceptometry and current magnetometry on some test samples using these nano-SQUIDs.

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Source: https://tomesphere.com/paper/1903.11262