| Project/Area Number |
16340097
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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 |
Condensed matter physics II
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| Research Institution | Tohoku University |
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Principal Investigator |
MAEKAWA Sadamichi Tohoku University, Institute for Materials, Research Professor, 金属材料研究所, 教授 (60005973)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUYAMA Hidetoshi Tokyo University of Science, Graduate school of Science, Professor, 理学部, 教授 (10004441)
TOHYAMA Takami Kyoto University, Yukawa Institute for Theoretical Physics, Professor, 基礎物理学研究所, 教授 (70237056)
TAKAHASHI Saburo Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (60171485)
KOSHIBAE Wataru Sendai National College of Technology, General Science, Associate Professor, 総合科学科, 助教授 (20273253)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,500,000 (Direct Cost: ¥15,500,000)
Fiscal Year 2006: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥5,800,000 (Direct Cost: ¥5,800,000)
Fiscal Year 2004: ¥6,200,000 (Direct Cost: ¥6,200,000)
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| Keywords | Spin Current / Orbital wave / Spin charge separation / Non-linear Optics / Thermopower / Spin electronics / Oxide electronics / Transition metal oxide / 量子キュービット / モット絶縁体 / 量子伝導 / π接合 / ジョセフソン効果 |
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| Research Abstract |
An electron has the internal degrees of freedom, spin・charge・orbital, which give rise to materials properties. The flow of charge of electrons is current, and electronics is based on the control of current. The electronics based on spin current is called spin-electronics. The dynamics of orbital is also expected in transition metal oxides.
In this project, the theory of quantum transport starting with the dynamics of these internal degrees of freedom of an electron has been constructed.
1.It is shown that the conversion between spin current and charge current can be obtained in a non-local spin Hall device together with an experimental group. Since the conversion is one of the Onsager reciprocal relations, it is a very basic concept in physics.
2.In a device consisting of superconductor/ferromagnet/superconductor tunnel junctions, the Josephson current flowing between two superconductors has the extra phase, π. This is called the π-junction. We have proposed that a superconducting ring with π-junction may be used as a quantum computing device (qubit) without applied magnetic field.
3.In several transition metal oxides such as Na_xCoO_2,we have shown that the orbital degeneracy causes an electronic lattice with is different from the crystal one. As a result, a variety of novel physical properties are expected. Based on the theory, we have formulated the anomalous Hall effect and giant thermopower observed in Na_xCoO_2.
In this project, we have investigated various quantum transport phenomena starting with the internal degrees of freedom of an electron.
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