Ac susceptibility and transport critical-current density of polycrystalline c-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films: Josephson tunneling and d-wave pairing

Journal Article · Tue Dec 31 23:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.1254· OSTI ID:474661

Widder, W; Bauernfeind, L; Braun, H F ^[1]; Burkhardt, H; Rainer, D ^[2]; Bauer, M; Kinder, H ^[3]

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1. Experimentalphysik V, Universitaet Bayreuth, D-95440 Bayreuth (Germany)
2. Theoretische Physik III, Universitaet Bayreuth, D-95440 Bayreuth (Germany)
3. Institut fuer Festkoerperphysik und Technische Physik, Technische Universitaet Muenchen, D-85747 Garching (Germany)

We determined the intergranular critical-current density j{sub cJ}(T) of thin films of polycrystalline c-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} by measuring the isothermal ac susceptibility {chi}(h{sub ac}) at zero dc magnetic field. The temperature dependence of j{sub cJ} was obtained from the temperature-dependent position of the intergrain peak in {chi}{sup {double_prime}}(h{sub ac}). We confirmed our results by measurements of the transport critical current performed under self-field conditions. The observed temperature dependence of the critical current was compared with calculations of the Josephson critical current across rough interfaces. The experimental data can be explained by either assuming d-wave symmetry of the superconducting order parameter or, alternatively, by assuming s-wave symmetry and unusually strong pair breaking at the grain boundaries. The calculated critical currents show temperature dependences significantly different from the Ambegaokar-Baratoff formula, and agree well with recent measurements on single grain boundary junctions. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 474661
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 2 Vol. 55; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
BARIUM COMPOUNDS
BARIUM OXIDES
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CURRENT DENSITY
HIGH-TC SUPERCONDUCTORS
JOSEPHSON EFFECT
MAGNETIC SUSCEPTIBILITY
OXYGEN COMPOUNDS
PAIRING INTERACTIONS
SUPERCONDUCTING FILMS
TEMPERATURE DEPENDENCE
TEXTURE
THIN FILMS
TUNNEL EFFECT
YTTRIUM COMPOUNDS
YTTRIUM OXIDES