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

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.

References in corpus (4)

• Imaging of super-fast dynamics and flow instabilities of superconducting vortices
• A Terraced Scanning Superconducting Quantum Interference Device Susceptometer with Sub-Micron Pickup Loops
• Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$ monolayer
• Frustrated ferromagnetic transition in AB-stacked honeycomb bilayer