| Project/Area Number |
13640353
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MATSUDA Yuji Institute for Solid State Physics, Associate Professor, 物性研究所, 助教授 (50199816)
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| Co-Investigator(Kenkyū-buntansha) |
IZAWA Koich Institute for Solid State Physics, Research Associate, 物性研究所, 助手 (90302637)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Josephson junction / Flux flow / High-Tc superconductor / Shapiro step / Quantum region / Charging effect / Superconducting gap / Bi : 2212 / 高温超伝導 / ジョセフソン効果 / 微細加工 / ジョセフソンボルテックス / マイクロ波 / クーロンブロッケイド / Bi : 2212 / フラックスロー / 有機超伝導 |
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| Research Abstract |
Highly anisotropic high-Tc superconductors, such as Bi : 2212, can be considered as stacks of superconducting CuO_2 layers coupled by the Josephson interaction. Several properties which have never been observed in single Josephson junctions made from conventional low-Tc materials have been found, which are associated with the multilayer structure and with the atomic thickness of the superconducting layers. In particular, the vortex phase diagram and the related electromagnetic properties of HTSC in the presence of a strong magnetic field parallel to the layers have been the subject of recent intense experimental and theoretical studies. In this project, we report the first observation of Shapiro steps in the Josephson flux flow state of Bi : 2212 stacked junctions. When the junction is irradiated at microwave frequencies in a strong parallel magnetic field, a steep increase of the current is observed in the dc current-voltage characteristics when the external microwave frequency and the Josephson frequency are harmonically related. The existence of Shapiro steps in the Josephson flux flow state is strong evidence of coherent motion of the Josephson vortex lattice through the whole thickness of the stack.
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