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arXiv · 0901.0308

A Terraced Scanning Superconducting Quantum Interference Device Susceptometer with Sub-Micron Pickup Loops

Nicholas C. Koshnick·Martin E. Huber·Julie A. Bert·Clifford W. Hicks·Jeff Large·Hal Edwards·Kathryn A. Moler
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Abstract

Superconducting Quantum Interference Devices (SQUIDs) can have excellent spin sensitivity depending on their magnetic flux noise, pick-up loop diameter, and distance from the sample. We report a family of scanning SQUID susceptometers with terraced tips that position the pick-up loops 300 nm from the sample. The 600 nm - 2 um pickup loops, defined by focused ion beam, are integrated into a 12-layer optical lithography process allowing flux-locked feedback, in situ background subtraction and optimized flux noise. These features enable a sensitivity of ~70 electron spins per root Hertz at 4K.

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Nicholas C. Koshnick, Martin E. Huber, Julie A. Bert, Clifford W. Hicks, Jeff Large, Hal Edwards, Kathryn A. Moler. 2009-01-03. A Terraced Scanning Superconducting Quantum Interference Device Susceptometer with Sub-Micron Pickup Loops. https://doi.org/10.1063/1.3046098

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