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arXiv · 2209.10748

Flux focusing with a superconducting nano-needle for scanning SQUID susceptometry

B. K. Xiang·S. Y. Wang·Y. F. Wang·J. J. Zhu·H. T. Xu·Y. H. Wang
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Abstract

Nano-fabricated superconducting quantum interference device (nano-SQUID) is a direct and sensitive flux probe useful for magnetic imaging of quantum materials and mesoscopic devices. Enabled by functionalities of superconductive integrated circuits, nano-SQUID fabricated on a chip is particularly versatile but spatial resolution has been limited by its planar geometry. Here, we use femtosecond-laser 3-dimensional (3D) lithography and print a needle onto a nano-SQUID susceptometer to overcome the limit of a plane-structure. The nano-needle coated with a superconducting shell focuses the flux both from the field coil and the sample. We perform scanning imaging using such a needle-on-SQUID (NoS) device on superconducting test patterns with topographic feedback. The NoS shows improved spatial resolution in both magnetometry and susceptometry over its planarized counterpart. This work serves as a proof-of-principle for the integration and inductive coupling between superconducting 3D nano-structures and on-chip Josephson nano-devices.

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B. K. Xiang, S. Y. Wang, Y. F. Wang, J. J. Zhu, H. T. Xu, Y. H. Wang. 2022-09-22. Flux focusing with a superconducting nano-needle for scanning SQUID susceptometry. https://doi.org/10.1038/s41378-023-00553-9

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