Bicrystal YBCO dc squids with low noise

Conference · Sat Aug 01 04:00:00 EDT 1992

OSTI ID:6965404

Miklich, A H; Koelle, D; Dantsker, E; Nemeth, D T; Kingston, J J; Kromann, R F; Clarke, J

We have fabricated 12 dc SQUIDs by laser depositing YBa[sub 2]Cu[sub 3]O[sub 7-x] on a SrTiO[sub 3] bicrystal substrate with a misorientation angle of 24*. At 77K all twelve devices had acceptable values of critical current, resistance and voltage modulation produced by an external magnetic field. The white noise energy of one device with an estimated inductance of 41 pH was 1.8 [times] 10[sup [minus]30] JHz[sup [minus]1]. The noise power scaled as 1/f at frequencies below about 1kHz, however, by using a bias current reversal scheme we were able to reduce this noise by two orders of magnitude at 1 Hz, to a value of about 1.5 [times] 10[sup [minus]29] JHz[sup [minus]1]. We made a magnetometer by coupling the SQUID to a flux transformer with a 5-turn input coil. The measured magnetic field gain was 60, and the white noise 36fT Hz[sup [minus][1/2]]. However, the transformer produced relatively large levels of 1/f flux noise, not reduced by the bias reversal scheme, that limited the noise at 1 Hz to 1.7 pT Hz[sup [minus][1/2]]. A single-layer magnetometer with a single-turn pick up loop is briefly described.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOE; CCTP; DFG; FJHFOUN; USDOE, Washington, DC (United States); California Competitive Technology Program, CA (United States); Deutsche Forschungsgemeinschaft, Bonn (Germany); Fannie and John Hertz Foundation (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6965404
• Report Number(s): LBL-32891; CONF-920802--45; ON: DE93004779
• Country of Publication: United States
• Language: English

Related Subjects

665412* -- Superconducting Devices-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
BICRYSTALS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTALS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
MAGNETOMETERS
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
OXIDES
OXYGEN COMPOUNDS
POLYCRYSTALS
SQUID DEVICES
STRONTIUM COMPOUNDS
STRONTIUM TITANATES
SUBSTRATES
SUPERCONDUCTING DEVICES
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES