Flux quantization in weak links in melt-textured bulk YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}}

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.51.16289· OSTI ID:55088

Wosik, J; Xie, L M; Wolfe, J C ^[1]; Ren, Y; Chu, C W ^[2]

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1. Texas Center for Superconductivity at University of Houston and Electrical Engineering Department, University of Houston, Houston, Texas 77204 (United States)
2. Texas Center for Superconductivity at University of Houston and Physics Department, University of Houston, Houston, Texas 77204 (United States)

We have studied flux quantization in weak links of {ital a}-{ital b}- and {ital a}({ital b})-{ital c}-plane-oriented, melt-textured YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} using a modulated-field microwave-absorption method. First derivative of the microwave absorption versus dc magnetic field was measured in a TE{sub 102} cavity at 9.5 GHz. We observed several series of well-resolved equally spaced absorption lines in the externally applied dc magnetic field with separation ranging from 6 {mu}T to 2.3 mT. By analyzing the dependence of these series on microwave power, temperature, and orientation of the sample versus dc magnetic field we have identified the types and locations of Josephson-junction weak links in the samples. One of the series was found to be related to the microwave absorption in a strongly coupled superconductor--normal-metal--superconductor type of junction located in intragrain plane defects (complex twin boundaries). For this junction, the critical current {ital I}{sub {ital c}} dependence on magnetic field {ital B} as well as lower critical field {ital B}{sub {ital c}1{ital J}} were determined. For the location of the inter- and intragrain plane defects we have found {ital C}{sub 2} and {ital C}{sub 4} symmetry, respectively. A physical model of microwave absorption in nonuniform Josephson junctions is presented and sample microstructure is correlated with the measurement results.

• OSTI ID: 55088
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 22 Vol. 51; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ABSORPTION SPECTRA
BARIUM OXIDES
COPPER OXIDES
CRITICAL CURRENT
FLUX QUANTIZATION
HIGH-TC SUPERCONDUCTORS
JOSEPHSON JUNCTIONS
MAGNETIC FIELDS
MICROWAVE RADIATION
TEMPERATURE DEPENDENCE
YTTRIUM OXIDES