| Project/Area Number |
01420007
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Grant-in-Aid for Scientific Research (A) |
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Principal Investigator |
KOBAYASHI Sun-ichi Univ. of Tokyo. Physics, Professor, 理学部, 教授 (90029471)
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| Co-Investigator(Kenkyū-buntansha) |
KATUMOTO Shingo Univ. of Tokyo. Physics, Research Assistant, 理学部, 助手 (10185829)
OOTUKA Youiti Univ. of Tokyo. Cryogenic Center, Associate Prof., 低温センター, 助教授 (50126009)
小森 文夫 東京大学, 理学部, 助手 (60170388)
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| Project Period (FY) |
1989 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥22,900,000 (Direct Cost: ¥22,900,000)
Fiscal Year 1991: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1989: ¥17,900,000 (Direct Cost: ¥17,900,000)
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| Keywords | mesoscopic / interference / small particles / superconductivity / SET / phase / Coulomb blockade / 臨界面低抗 / 電子線描面 / 微小トンネル接合 / 干渉効果 / 微小なトンネル接合 / 帯電効果 / 巨視的量子トンネル効果 / 電子線リソグラフィ- / 帯電エネルギ- / ジョセフソン効果 |
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| Research Abstract |
The aim of this study is to observe the electron wave interference effects in well-controlled mesoscopic metals with submicron structures. We used two types of samples ; one prepared by using the electron lithography method and the other the small particles which were slightly oxidized and connected two-dimentionaly.
As for the small particle samples, two dimensional random networks of Josephson junctions in which the electrodes were aluminium particles of 15A in diameter were investigated. It is confirmed that the global superconducting coherence appears when the normal sheet resistance is smaller than R_Q=h/4eX^2. From this result and the previous one for tin films, we conclude that this critical sheet resistance is universal. By applying the magnetic field perpendicular to the films, it is also confirmed that the critical sheet resistance associated with the, transition from superconducting to insulating phases is R_Q=h/4e^<2. >
The measurement of the magnetoresistance of very resistive aluminium films suggested that the isolated aluminium particle is not superconducting.
We set up the electron beam drawing machine and optimized various conditions for drawing. By using it, we prepared the one-dimensional array of very small junctions and observed the Coulomb blockade which takes place when the charging energy associated with a single electron tunneling is larger than the thermal energy. The single electron tunneling oscillation was observed as the structures in the dc I-V characteristics when the junctions were irradiated with an external microwave.
We prepared two point contacts connected in parallel on the two dimensional electron system in the semiconductor heterojunction with the use of microfablicated gates. We showed that the interference pattern changes when the width of one of gate is changed. This is a new method to tune the electron phase after the vector potential and the static potential.
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