2007 Fiscal Year Final Research Report Summary
Theoretical Study on Novel Physical Properties of Nano-scale Exotic Superconductors
| Project/Area Number |
18510090
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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 |
Nanostructural science
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| Research Institution | Tohoku University |
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Principal Investigator |
EBISAWA Hiromichi Tohoku University, professor emerittus (90005439)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Masahiko Akita University, Faculty of Education and Human Studies, Associate Professor (60301040)
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| Project Period (FY) |
2006 – 2007
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| Keywords | exotic superconductor / high Tc superconductor / multiple Josephson junction / scanning SQUID microscope / topological crystals / phase defects / nano-scale superconductor / noise reduction |
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| Research Abstract |
Aiming to develop a frontier of novel physics in nano-scale exotic superconductors, several studies have been advanced.
(1) Numerical studies on multiple Josephson junctions in d-wave high-Tc superconductors: By numerically solving differential equations describing the time evolution of the phase differences, we have observed that the localized oscillation modes, which correspond to the breather modes in sine-Gordon equation, causes a non-zero voltage in superconducting state, thus driving the transition to resistive state. These modes actually work as "seeds" inducing the transition.
(2) A procedure to improve the resolution of the images of scanning SQUID microscope is studied, which is useful in observing the magnetic field distribution in d-wave/s-wave (or p-wave/s-wave) hybrid superconducting systems. In order to minimize the effects of noise and finite coil size, numerical simulation is advanced and comparison with experiments is made. The difficulty in application to images with non-zero magnetic field near the edges has been overcome with the help of the simulations.
(3) To exemplify of the effects of sample geometry, we have studied the distribution of dislocations in tiny ring-shaped crystals and found several different dislocation distributions. To be more precise, ring-shaped topological crystals of NbSe3 etc. are studied within linear elastic theory. The uniform distribution of dislocations in crystals with circumferences larger than 1 micron is predicted. Below this size, the destruction of elastic coupling can take place.
(4) The effects of superconducting fluctuations in the conductivity of tiny superconducting networks are studied. Under an AC current noise, a Shapiro-step-like structure appears in the current-voltage characteristics of current-biased system, causing an anomalous nonlinear resistivity.
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[Presentation] ナノサイズの異方的超伝導体2006
Author(s)
加藤勝, 小山富男, 町田昌彦, 林正彦, 海老澤丕道, 石田武和
Organizer
第14回渦糸物理国内会議
Place of Presentation
登別(北海道)
Year and Date
2006-12-19
Description
「研究成果報告書概要(和文)」より
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[Presentation] Nanosize Anisotropic Superconductors2006
Author(s)
Masaru Kato, Tomio Koyama, Masahiko Machida, Masahiko Hayashi, Hiromichi Ebisawa, Takekazu Ishida
Organizer
14^<th> Domestic Workshop on Vortex Physics
Place of Presentation
Noboribetsu, Hokkaido
Year and Date
2006-12-19
Description
「研究成果報告書概要(欧文)」より
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[Presentation] SQUID顕微鏡の画像解析について2006
Author(s)
林正彦, 海老澤丕道, 清水真, 安部泰司, 松島吉明, 石田武和, 佐藤和郎, 四谷任
Organizer
第14回渦糸物理国内会議
Place of Presentation
登別(北海道)
Year and Date
2006-12-18
Description
「研究成果報告書概要(和文)」より
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[Presentation] On image processing for SQUID microscope2006
Author(s)
Masahiko Hayashi, Hiromichi Ebisawa, Makoto Shimizu, Taiji Abe, Yoshiaki Matsushima, Takekazu Ishida, Kazuo Satoh, Tsutomu Yotsuya
Organizer
14^<th> Domestic Workshop on Vortex Physics
Place of Presentation
Noboribetsu, Hokkaido
Year and Date
2006-12-18
Description
「研究成果報告書概要(欧文)」より
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