Phase diagram of flux creep in melt-textured and single-crystalline YBa[sub 2]Cu[sub 3]O[sub 7[minus][delta]]

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.7016· OSTI ID:6735913

Kuepfer, H ^[1]; Gordeev, S N ^[2]; Jahn, W; Kresse, R; Meier-Hirmer, R; Wolf, T ^[1]; Zhukov, A A ^[3]; Salama, K; Lee, D ^[4]

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1. Kernforschungszentrum Karlsruhe, Institut fuer Technische Physik Universitaet Karlsruhe, Postfach 3640, 76021 Karlsruhe (Germany)
2. Kernforschungszentrum Karlsruhe, Institut fuer Technische Physik, Karlsruhe (Germany) Moscow Institute of Radioengineering, Electronics Automation, 117454 Moscow (Russian Federation)
3. Kernforschungszentrum Karlsruhe, Institut fuer Technische Physik, Karlsruhe (Germany) Physics Department, Moscow State University, 117234 Moscow (Russian Federation)
4. Department of Mechanical Engineering, Texas Center of Superconductivity at University of Houston, Houston, Texas 77204 (United States)

Voltage-current characteristics [ital E]([ital j]) were obtained from relaxation and magnetization measurements in melt-textured and single-crystalline YBa[sub 2]Cu[sub 3]O[sub 7[minus][delta]]. Both samples show a change of the [ital E]([ital j]) behavior, which is in accordance with a vortex-glass--vortex-liquid transition. In the ([ital B],[ital T]) range below this transition, log[ital E](log[ital j]) curves pass from a negative to a positive curvature with increasing current. Collective-creep or vortex-glass theory are in agreement with the experimental observation below the corresponding inflection point, whereas above, the exponential [ital E]([ital j]) dependence of the Anderson model is the better approximation. The exponent [mu] from the collective creep model was used for the analysis of the [ital E]([ital j]) dependence in both regimes. Because [mu] varies with the current, mean values were taken within a constant current window for consistency. With increasing magnetic fields, [mu] passes a maximum, approaches zero, and becomes [minus]1. The transformation from collective creep into the Anderson creep occurs at the end of the plateau of [ital S] at which [mu] changes from positive to negative. Finally, it is argued that the maximum of the current at intermediate magnetic fields (the fishtail effect) is not based on relaxation.

• OSTI ID: 6735913
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:10; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
CRITICAL CURRENT
CUPRATES
CURRENTS
ELECTRIC CURRENTS
HIGH-TC SUPERCONDUCTORS
MAGNETIC FLUX
MAGNETIC PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC ACTIVITY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES