Presentation	2001/4/18 Characteristics of high Tc SQUID magnetometers with flux dams H. Oyama, S. Hirano, M. Matsuda, S. Kuriki,
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Abstract(in English)	In order to operate high-T_c SQUID magnetometers in earth field without magnetic shielding, we incorporated flux dams (FDs) in direct-coupled YBCO SQUIDs. When the magnetometers were cooled in static magnetic fields, the low-frequency noise (designated by the field noise at 1Hz: B_n(1Hz)) increased from the value of less than 1pT/Hz^<1/2> to a higher value of more than 2pT/Hz^<1/2> for the applied field exceeding 25μT. For the reason of this B_n increase, we speculate flux trapping within the area of the film around the FD. When external field B_ above 0.5μT was applied to the magnetometer after zero field cooling, the FLL output became fluctuated and B_n (1Hz) was increased, but bccame stable after a time. This relaxation time was longer and the residual B_n was higher for larger applied field. Since many vortices (10^3-10^4) move along the grain boundary of FD, we speculate that trapping of them in the surrounding film may take place and produce B_n by thermal fluctuation.
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Keyword(in English)	SQUID magnetometer / flux dam / field cool / zero field cool
Paper #	SCE2001-1,MW2001-1
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Committee	SCE
Conference Date	2001/4/18(1days)
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Registration To	Superconductive Electronics (SCE)
Language	JPN
Title (in Japanese)	(See Japanese page)
Sub Title (in Japanese)	(See Japanese page)
Title (in English)	Characteristics of high Tc SQUID magnetometers with flux dams
Sub Title (in English)
Keyword(1)	SQUID magnetometer
Keyword(2)	flux dam
Keyword(3)	field cool
Keyword(4)	zero field cool
1st Author's Name	H. Oyama
1st Author's Affiliation	Research Institute for Electronic Science, Hokkaido University()
2nd Author's Name	S. Hirano
2nd Author's Affiliation	Research Institute for Electronic Science, Hokkaido University
3rd Author's Name	M. Matsuda
3rd Author's Affiliation	Muroran Institute of Technology
4th Author's Name	S. Kuriki
4th Author's Affiliation	Research Institute for Electronic Science, Hokkaido University
Date	2001/4/18
Paper #	SCE2001-1,MW2001-1
Volume (vol)	vol.101
Number (no)	23
Page	pp.pp.-
#Pages	6
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