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High temperature superconductor dc-SQUID microscope with a soft magnetic flux guide

 
: Poppe, U.; Faley, M.I.; Zimmermann, E.; Glaas, W.; Breunig, I.; Speen, R.; Jungbluth, B.; Soltner, H.; Halling, H.; Urban, K.

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Superconductor Science and Technology 17 (2004), Nr.5, S.S191-S195
ISSN: 0953-2048
ISSN: 1361-6668
Englisch
Zeitschriftenaufsatz
Fraunhofer ILT ()

Abstract
A scanning SQUID microscope based on high-temperature superconductor (FITS) dc-SQUIDs was developed. An extremely soft magnetic amorphous foil was used to guide the flux from room temperature samples to the liquid-nitrogen-cooled SQUID sensor and back. The flux guide passes through the pick-up loop of the HTS SQUID, providing an improved coupling of magnetic flux of the object to the SQUID. The device measures the z component (direction perpendicular to the sample surface) of the stray field of the sample, which is rastered with submicron precision in the x-y direction by a motorized computer-controlled scanning stage. A lateral resolution better than 10 mum, with a field resolution of about 0.6 nT Hz(-1/2) was achieved for the determination of the position of the current carrying thin wires. The presence of the soft magnetic foil did not significantly increase the flux noise of the SQUID.

: http://publica.fraunhofer.de/dokumente/N-38414.html