Bechstein, S*; Kirste, A*; Drung, D*; Regin, M*; Kazakova, O; Gallop, J; Hao, L; Cox, D; Schurig, T* (2013) Investigation of material effects with micro-sized SQUID sensors. IEEE Trans. Appl. Supercond., 23 (3). 1602004

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Abstract

Micro-sized SQUID sensors have been designed and fabricated in conventional Nb/AlOx/Nb junction technology. Two types are presented here: a microSQUID gradiometer with two small loops, each with a diameter of 3 µm, and an integrated susceptometer having 30 µm or 60 µm circular loops and on-chip field coils. Both sensor types have been read out by a SQUID array, acting as a low-noise preamplifier. The microSQUIDs were operated in a temperature range of 4.2 K to 7 K, whereas the susceptometers are rather intended for operation below 4.2 K. Important SQUID parameters such as flux noise, maximum operation field, and nonlinearity were measured at different temperatures. The best white flux noise level achieved with a microSQUID was 135 nf(0)/Hz(1/2) at 4.2 K. Micro-sized magnetic beads were investigated with microSQUIDs, whereas susceptometers were used to measure the susceptibility of thin wires up to 100 kHz.

Item Type:	Article
Keywords:	Linearity, magnetic susceptibility, particle measurements, SQUIDs, superconducting coils, superconducting device noise, superconducting integrated circuits
Subjects:	Quantum Phenomena Quantum Phenomena > Quantum Information Processing and Communication
Identification number/DOI:	10.1109/TASC.2012.2235505
Last Modified:	02 Feb 2018 13:14
URI:	https://eprintspublications.npl.co.uk/id/eprint/5716