Possibility of critical field enhancement due to field penetration in high-T/sub c/ sponges and thin films

Conference · Wed Mar 01 00:00:00 EST 1989 · IEEE Trans. Magn.; (United States)

OSTI ID:5886075

Collings, E W; Markworth, A J; Marken, Jr, K R

Magnetic susceptibility measurements of a sample of sintered high-T/sub c/ ceramic superconductor of nominal composition Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-y/ were conducted as function of temperature from liquid-He temperatures to T/sub c/. The fitted form of the susceptibility temperature dependence yielded a sample particle size that was only a few times larger than the field-penetration depth. The particle size was much less than the grain size and commensurate with the thickness of the optical twins. The occurence of field penetration between lamina about 0.2 to 0.7 /mu/m in half-thickness was predicted to lead to a small enhancement of the lower critical field. This prediction was compared with the results of an experiment in which the M(H) field sweep, initially +- 100 gauss, was incremented in small steps up to several kgauss. The results of the enhancement studies are also discussed in the light of Bean's early experiments on Pb sponges (in this case /lambda/ >> particle size) which exhibited spectacular enhancements of H/sub c/ in association with flux trapping at or between the Pb filaments. It is predicted that it should be possible, using presently available film-deposition techniques, to produce high-T/sub c/ films possessing several-fold enhancements of H/sub cl/ beyond the bulk value; and that as with the Pb sponges, the magnetization loops, even when taken within what passes for the Meissner state in such materials, will by hysteretic.

• Research Organization: 0747000
• OSTI ID: 5886075
• Report Number(s): CONF-880812-; TRN: 89-018615
• Journal Information: IEEE Trans. Magn.; (United States), Vol. 25:2; Conference: Applied superconductivity conference, San Francisco, CA, USA, 21-25 Aug 1988
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
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36 MATERIALS SCIENCE
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
SINTERING
COPPER OXIDES
SUPERCONDUCTING FILMS
CHEMICAL COMPOSITION
YTTRIUM OXIDES
CALCULATION METHODS
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYSTERESIS
LEAD
MAGNETIC SUSCEPTIBILITY
MEISSNER-OCHSENFELD EFFECT
PARTICLE SIZE
SUPERCONDUCTIVITY
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ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
FABRICATION
FILMS
INFORMATION
MAGNETIC PROPERTIES
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SIZE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
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