A high performance Nb nano-SQUID with a three-dimensional structure

Abstract

A superconducting quantum interference device (SQUID) miniaturized into nanoscale is promising in the inductive detection of a single electron spin. A nano-SQUID with a strong spin coupling coefficient, a low flux noise, and a wide working magnetic field range is highly desired in a single spin resonance measurement. Nano-SQUIDs with Dayem-bridge junctions excel in a high working field range and in the direct coupling from spins to the bridge. However, the common planar structure of nano-SQUIDs is known for problems such as a shallow flux modulation depth and a troublesome hysteresis in current-voltage curves. Here, we developed a fabrication process for creating three-dimensional (3-D) niobium (Nb) nano-SQUIDs with nano-bridge junctions that can be tuned independently. Characterization of the device shows up to 45.9 % modulation depth with a reversible current-voltage curve. Owning to the large modulation depth, the measured flux noise is as low as 0.34 μΦ${}_0$/Hz${}^{1/2}$. The working field range of the SQUID is greater than 0.5 T parallel to the SQUID plane. We believe that 3-D Nb nano-SQUIDs provide a promising step toward effective single-spin inductive detection.

23 pages, 4 figures

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Cited by in corpus (11)

• Grooved Dayem nanobridges as building blocks of high-performance YBa${}_2$Cu${}_3$O${}_{7-\delta }$ SQUID magnetometers
• 3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materials
• Miniaturization of the Superconducting Memory Cell via a Three-Dimensional Nb Nano-Superconducting Quantum Interference Device
• Sensitive spin detection using an on-chip SQUID-waveguide resonator
• Josephson Coupling in the Dissipative State of a Thermally Hysteretic $\mu$-SQUID
• Gate-Tunable Critical Current of the Three-Dimensional Niobium Nano-Bridge Josephson Junction
• Nano-bridge Superconducting Quantum Interference Devices: beyond the Josephson limit
• Geometric Scaling of the Current-Phase Relation of Niobium Nano-Bridge Junctions
• Millikelvin Nb nanoSQUID-embedded tuneable resonator fabricated with a neon focused-ion-beam
• Dual on-chip SQUID measurement protocol for flux detection in large magnetic fields
• Improving spatial resolution of scanning SQUID microscopy with an on-chip design