| Project/Area Number |
09640463
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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 |
物性一般(含基礎論)
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| Research Institution | Osaka University |
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Principal Investigator |
MATSUKAWA Hiroshi Graduate School of Science, Osaka University, associate Professor, 大学院・理学研究科, 助教授 (20192750)
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| Co-Investigator(Kenkyū-buntansha) |
松川 宏 大阪大学, 大学院・理学研究科, 助教授 (20192750)
小谷 岳生 大阪大学, 大学院・理学研究科, 助手 (60283826)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | friction / pinning / macroscopic quantum effect / quantum tunneling / CDW / magnetic flux lattice / ラチェット / フレンクル-コントローヴァモデル / 解析性の破れ / 清浄表面 / ランダムネス / トンネル効果 |
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| Research Abstract |
We have studied the frictional phenomena of a 2-dimensional model in the presence of the periodic potential in addition to impurities. This model can be applied also to the magnetic flux lattice in film superconductors. It turned out that impurity can diminishes the static frictional force, there is a kind of quasi long range order in the moving lattice even in the presence of impurities and so on. This order exists in the transverse direction for any magnitude of the velocity and cause the transverse pinning, that is, the direction of motion does not change even though we apply external force in the transverse direction. Typical length scale of the order grows with increasing velocity and cause a peculiar behavior of the kinetic frictional force and the transverse pinning force. The velocity dependence of the latter becomes nonmonotonic, which is caused by the change of the discommensurate structure.
CDW nonlinear electric conduction which is the manifestation of the macroscopic quantum tunneling is observed in experiments. Two-probe method was employed in the experiments. In order to observe the tunneling currents by this method both CDW's near the electrode and in the bulk must move by quantum tunneling. We have explained the experiments by considering both vortex ring formation as the tunneling process near the electrode and the kink-antikink pair formation as that in the bulk.
We have calculated the flow and the work of two kinds of quantum ratchet model and shown that the flow of these systems is the manifestation of the new quantum mechanical phenomena resulting from the interaction with the heat bath.
We have discussed the quantum tunneling of the commensurate CDW and shown that the impurity can assist the tunneling.
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