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 μm in diameter and the flux noise was around 1 μΦ0/Hz at 100 Hz. We demonstrate scanning magnetometry, susceptometry and current magnetometry on some test samples using these nano-SQUIDs.
@article{arxiv.1903.11262,
title = {3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materials},
author = {Y. P. Pan and S. Y. Wang and X. Y. Liu and Y. S. Lin and L. X. Ma and Y. Feng and Z. Wang and L. Chen and Y. H. Wang},
journal= {arXiv preprint arXiv:1903.11262},
year = {2019}
}