Direct observation of anisotropic flux penetration in twinned YBa2Cu3O7−x single and polycrystals
| Autor: | Debra L. Kaiser, V.K. Vlasko-Vlasov, M. Turchinskaya, V. I. Nikitenko, A.A. Polyanskii, Alexander L. Roytburd, Frank W. Gayle, Alexander J. Shapiro |
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| Rok vydání: | 1993 |
| Předmět: |
Flux penetration
Materials science Flux pinning Condensed matter physics Energy Engineering and Power Technology Condensed Matter Physics Magnetic flux Electronic Optical and Magnetic Materials Electromagnetic induction Condensed Matter::Superconductivity Flux flow Grain boundary Electrical and Electronic Engineering Crystal twinning Anisotropy |
| Zdroj: | Physica C: Superconductivity. 216:205-210 |
| ISSN: | 0921-4534 |
| Popis: | We report microscopic maps of magnetic induction in YBa 2 Cu 3 O 7− x crystals which directly show a correlation of flux penetration with twin boundary orientation and twin density. These maps were obtained by means of a recently-improved magneto-optical imaging technique. Pinning was lowest in untwinned regions and increased with increasing twin density. Even at low temperatures (6 K), twin boundaries led to a large anisotropy in flux pinning. This anisotropy, defined as the ratio of the magnetic induction gradient across twin boundaries to that along twin boundaries, was 10 at 17 K; this ratio increased with increasing temperature. In polycrystals, twin boundaries also had a strongly anisotropic effect on flux flow into a grain from a grain boundary. |
| Databáze: | OpenAIRE |
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