Evidence of Kosterlitz-Thouless transition in YBa2Cu3O7/ PrBa2Cu3O7 superlattice films
| Autor: | David K. Christen, C.E. Klabunde, James R Thompson, H. R. Kerchner, J.O. Thompson, Yang Ren Sun |
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| Rok vydání: | 1992 |
| Předmět: |
Superconductivity
High-temperature superconductivity Flux pinning Materials science Condensed matter physics Superlattice Energy Engineering and Power Technology Condensed Matter Physics Electronic Optical and Magnetic Materials law.invention Kosterlitz–Thouless transition Van der Pauw method law Condensed Matter::Superconductivity Electrical and Electronic Engineering Thin film Anisotropy |
| Zdroj: | Physica C: Superconductivity. 198:75-80 |
| ISSN: | 0921-4534 |
| DOI: | 10.1016/0921-4534(92)90268-h |
| Popis: | Experimental measurements of four-terminal (van der Pauw) transport-current resistivity and of dynamic AC magnetic response of certain superlattice films show broad resistive transitions and frequency-dependent magnetic transitions into the superconductive state. Such observations indicate that the superconductive critical temperature is not described by mean-field theory. pitaxial, c ⊥ superlattice films of YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 were grown in situ by laser ablation. Layer thicknesses of each compound ranged from two to four atomic cells. While material inhomogeneity can produce such a broad resistive transition,it would prevent our observation of a relatively sharp step-like transition in the inductive impedance. Such response must arise due to vibrations of pinned and bound supercurrent vortices. Observation of the Kosterlitz-Thouless (K-T) transition of bound vortices is expected to occur in a two-dimensional system. We see apparent K-T transitions only in films of thin (two or three atomic-lattice cells) Y-compound layers and thick Pr-compound layers. This systematically implies that extreme anisotropy of CuO superconductors can be tied to observations of two-dimesional physical phenomena. |
| Databáze: | OpenAIRE |
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