| Project/Area Number |
11640320
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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Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Faculty of Education, Yamagata University (2000-2001)
Osaka City University (1999) |
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Principal Investigator |
NONOYAMA Shinji (2000-2001) Faculty of Education, Yamagata University, Associate Professor, 教育学部, 助教授 (50221487)
小栗 章 (1999) 大阪市立大学, 理学部, 助教授 (10204166)
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| Co-Investigator(Kenkyū-buntansha) |
OGURI Akira Faculty of Science, Osaka City University, Associate Professor, 理学部, 助教授 (10204166)
ISHII Hiroumi Faculty of Science, Osaka City University, Professor, 理学部, 教授 (80047167)
野々山 信二 山形大学, 教育学部, 助教授 (50221487)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | quantum transport / mesoscopic systems / Coulomb interaction / electoron correlation / nonequilibrium current / nonlinear response / local current distribution / Keldysh Green function / 電子間相互作用 / Fermi流体 / 摂動論 / 非平衡電流分布 / 非平衡Green関数 / 磁場下の輸送現象 |
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| Research Abstract |
We have studied the conductance through small interacting systems connected to noninteracting leads based on the Kubo formalism, and have clarified that the conductance can be expressed in a Landauer type form also in the interacting systems: g = (2e^2/h)∫dε (-δf/δε)Τ(ε), where f(ε) is the Fermi function and Τ(ε) is the transmission probability which is defined in terms of the vertex function. We have applied this formulation to a series of quantum dots, and have shown that Τ(ε) has much information about the excitation spectrum. We have also studied nonequilibrium properties of the Kondo effects in quantum dots based the Anderson model under a finite bias voltage V using the Ward identities for the Keldysh Green function. It has been shown that for small but finite V the low-energy behaviors of the excitation spectrum and nonlinear response of the current can be described by the local Fermi-liquid theory.
We have also carried out the numerical calculations of the nonequilibrium current under a finite bias voltage. Using the recursive Green function technique in the Keldysh formalism, we have studied the spatial distribution of local currents in the presence of the magnetic field which is described by the Peierls phase. We have considered the current distribution in various systems. In a series of two point contacts, we have found that a large vortex is created in between the point contacts in the linear response regime of V, while there exists several small vortcies in the nonlinear regime. In a system which simulates a metal ring interrupted by two tunnel junctions, a local flow which corresponds to resonant tunneling connecting the edge states of the different sides has been observed. We have also applied the recursion method to tunneling phenomena in ferromagnetic and superconducting materials.
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