Observation of a three-dimensional vortex-line liquid in a highly {ital c}-axis-oriented (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub {ital x}} silver-sheathed tape
- Institute of Solid State Physics, Academia Sinica, Hefei 230031, People`s Republic of (China)
- Beijing General Research Institute of Nonferrous Metal, Beijing 100088, People`s Republic of (China)
- Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, People`s Republic of (China)
We have measured the temperature dependence of resistance of a highly {ital c}-axis-oriented (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub {ital x}} silver-sheathed tape in the mixed state using the dc flux transformer geometry. In the vortex fluid regime, we have observed the onset of a nonlocal conductivity which corresponds to the peak ({ital T}{sub peak}) in {ital R}{sub bot}({ital T}) curves. This can be explained qualitatively in terms of the vortex decoupling which arises from an increased thermal fluctuation. At {ital T}{lt}{ital T}{sub peak}, the vortices are three dimensional (3D) in character. This behavior is quite different from the results obtained recently by Safar {ital et} {ital al}. [Phys. Rev. Lett. {bold 69}, 824 (1992)] and Busch {ital et} {ital al}. [Phys. Rev. Lett. {bold 69}, 522 (1992)] in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} single crystals using the same measuring method. Their results show that the vortices are two dimensional in character. The difference of the vortex dimensionality between (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub {ital x}} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} superconductors in the vortex liquid regime may be attributed to different anisotropies due to their different crystal structures and pinning disorders. In a 3D vortex line liquid, the results reveal that dissipation seems to originate from the thermally activated plastic motion of a pinned vortex line liquid. The field and temperature dependence of the activation energy is as follows: {ital U}({ital H},{ital T})={ital U}{sub 0}(1{minus}{ital T}/{ital T}{sub {ital c}}){ital H}{sup {minus}0.45}. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 285972
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 2; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
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