Flux creep and penetration in Fe-doped YBa sub 2 Cu sub 3 O sub 7

Journal Article · Thu Mar 01 04:00:00 EST 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.4286· OSTI ID:6925588

Mohamed, M A; Jung, J; Franck, J P ^[1]

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1. Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G2J1 (CA)

Measurements of the magnetic-field distribution, flux penetration, and decay of trapped flux were performed for a disc-shaped sample of YBa{sub 2}Cu{sub 2.95}Fe{sub 0.05}O{sub 7{minus}{delta}} at 77 K. Time-dependent magnetic-flux penetration, i.e., a decay of diamagnetic shielding and the Meissner field, was observed for zero-field-cooled (ZFC) and field-cooled (FC) samples. The decays were found to be logarithmic in time. The logarithmic decay rate of diamagnetic shielding depends on an applied magnetic field and reaches its maximum at an applied field of about 30 G. The dependence of a trapped field versus an applied field shows a maximum at an applied field of 100 G for the FC case and 200 G for the ZFC case. The maximum amount of the trapped field is about two times less than that for a pure, undoped YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} sample of similar dimensions. The logarithmic decay rate of the trapped field versus the initial trapped field is described by a linear function with the change of its slope at the trapped field corresponding to an applied field of about 30 G for both the FC and ZFC cases. These results are related to the sample microstructure, i.e., grain size and porosity. Trapped field decays can be explained in terms of the interaction between intergranular vortices and persistent current circulating around normal regions or voids, in the framework of the conventional flux-creep model recently proposed by Hagen, Griessen, and Salomons (Physica 157C, 199 (1989)).

• OSTI ID: 6925588
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:7; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
GRAIN SIZE
IRON ADDITIONS
IRON ALLOYS
LOW TEMPERATURE
MAGNETIC FLUX
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
POROSITY
SIZE
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES