Comparison of pinning parameters between low-{ital T}{sub {ital c}} superconductors and YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}
- Forschungszentrum Karlsruhe, Institut fuer Technische Physik Universitaet Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany)
- Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76027 Karlsruhe (Germany)
- Department of Computer Science and Electronics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820 (Japan)
- Advanced Materials and Technology Research Laboratories, Nippon Steel Co., 1618 Ida, Nakahara-Ku, Kawasaki 211 (Japan)
- Department of Mechanical Engineering, Texas Center of Superconductivity at University of Houston, Houston, Texas 7704 (United States)
ac flux-profile measurements are used to determine the current density {ital j}, the reversible penetration depth {lambda}{prime} of a pinned flux lattice, and the reversible displacement {ital d}, which is the distance flux can move before being unpinned. Both parameters {lambda}{prime} and {ital d} describe the elastic regime of the interaction between vortices and defects whereas the current corresponds to the maximum elastic or plastic distortion. The influence of thermal relaxation on these parameters and on ac measurements in general is discussed. Anomalous features of the flux profiles observed in various low-{ital T}{sub {ital c}} superconductors are correlated with the saturation of the current based on plastic deformation of the vortex lattice. A comparison with flux profiles from single-crystalline and melt-textured YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} shows the same anomalous feature. This demonstrates the importance of plastic shear also in high-{ital T}{sub {ital c}} superconductors which seems to be present in the whole magnetic-field regime. Collective pinning and the related peak effect of the current in V{sub 3}Si are compared with the fishtail effect in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystals. The different magnetic-field dependences of {lambda}{prime} and {ital d} in the region of maximum current point to differences between these observations. Decreasing current correlated with decreasing {lambda}{prime} in specimens with a fishtail are related to a softening of the vortex lattice at fields below the maximum current. This anomalous feature is not observed in samples with a current continuously decreasing with magnetic field.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 115873
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 10 Vol. 52; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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