| Project/Area Number |
08454089
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Tokyo University |
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Principal Investigator |
KATSUMOTO Shingo Institute for Solid State Physics, University of Tokyo, Associate Professor, 物性研究所, 助教授 (10185829)
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| Co-Investigator(Kenkyū-buntansha) |
HIRASAWA Masakatsu Institute for Solid State Physics, University of Tokyo, Research Associate, 物性研究所, 助手 (90262162)
ENDO Akira Institute for Solid State Physics, University of Tokyo, Research Associate, 物性研究所, 助手 (20260515)
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| Project Period (FY) |
1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥8,900,000 (Direct Cost: ¥8,900,000)
Fiscal Year 1996: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Keywords | Single-electron transistor / mesoscopic superconductor / surface nucleation of superconductivity / magnetic periodic modulation / two dimensional electron / diluted magnetic semiconductor / photo-induced ferromagnetism / colossal magnetoresistance / メゾスコピック系 / 微小磁性体 / 微小超電導体 |
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| Research Abstract |
9-1 Fluxoid states of mesoscopic superconductors
It has been shown that the single-electron transistor structure is one of the best systems to investigate the superconducting states of mesoscopic materials by the following reasons.
(1)Because the energy gap is directly measured through the electric transport, the sensitivity is very high.
(2)The mesoscopic superconductor is well-isolated by the two tunnel junctions of the structure and the coupling to the surrounding environment is minimized.
Using this structure, we have shown that the order parameter of mesoscopic superconducting ring keeps its spatial single-valuedness though the number of the Cooper pair on the island is almost fixed. We found, also, that in the simply-connected superconductor (i.e.that without hole) the amplitude of the order parameter is large at the surface of the material.
9-2 Magnetic decoration of two-dimensional electron systems
We introduced periodic magnetic modulation of mesoscopic scale by nano-fabrication of ferromagnets. It had been difficult to detect the effect of the magnetic modulation because of the large effect of electrostatic modulation inevitably introduced by the strain and the image force. The problem was solved by utilizing the hysteresis effect of the ferromagnets and the clear observation was achieved.
9-3 Low temperature transport of diluted magnetic semiconductors
The first successful growth of a diluted magnetic semiconductor (Ga, Mn) As was reported. We also found colossal magnetoresistance in the ferromagnetic phase. Light-induced ferromagnetism was found in (In, Mn) As/GaSb heterostructure.
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