LTS SQUID sensor with a new configuration

• Published in: Superconductor science & technology Vol. 12; no. 11; pp. 806 - 808
• Main Authors: Stolz, R, Fritzsch, L, Meyer, H-G
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 01.11.1999; Institute of Physics
• Subjects: Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Magnetic components, instruments and techniques; Magnetometers for magnetic field measurements; Physics; Fabrication; SQUID devices; Superconducting junctions; SQUID magnetometers; Measurement sensor; White noise; Instrumentation; Field gradients; Magnetic fields; Niobium; Aluminium oxides
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/12/11/334

We have developed highly sensitive SQUID-based magnetometers and gradiometers, fabricated in a standard Nb/AlO sub(x)Nb technology. The SQUID itself is designed as a current sensor having an input coil and a feedback coil. The number of turns of the input coil can be adjusted to ensure optimal coupling to the pickup loops with an inductance in the range from 5 nH to 300 nH. Several types of planar pickup loop configurations have been realized. The magnetometer has a pickup loop with a size of 1 cm x 1 cm. With a typical white noise level better than 4 mu Phi sub(0) Hz super(- one half ) and an effective area of 2.6 mm super(2) a field resolution of 3.2 fT Hz super(- one half ) results for the magnetometer. Two loops connected in series with an area of 2 cm x 2 cm each and a baseline of 4 cm were used in the gradiometer. We measured a 7.5 mm super(2) effective area for each loop and a field gradient resolution of 36 fT m super(-1) Hz super(- one half ) corresponding to a field resolution in the loop of 1.6 fT Hz super(- one half ).