First Derivative High-Tc SQUID Gradiometers with Narrow Structure from Single Layer YBCO Thin Film

Mizushi MATSUDA  Tsutomu MATSUURA  Koichi KATO  Hiroshi OYAMA  Amane HAYASHI  Satoru HIRANO  Shinya KURIKI  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.3   pp.677-680
Publication Date: 2002/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Superconductive Electronics)
Category: SQUIDs and Their Applications
SQUID,  gradiometer,  low frequency noise,  

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We have fabricated and characterized two types of high-Tc planar SQUID gradiometers having different line width of pickup loops. The device worked in flux-locked loop (FLL) operation even in laboratory environment without any shielding. A magnetic field gradient resolution of a parallel-type device in a lightly shielded room was about 0.5 pT/cmHz1/2 at 1 kHz and 2 pT/cmHz1/2 at 1 Hz. The device was possible to record magnetocardiograms in a shielded room. QRS-complex peaks of about 10 pT PP/4mm are clearly observed. For a mesh-type device, the increase of low frequency noise in the open laboratory environment was less than that for a parallel-type.