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Theory of Quantum Transport based on Spin and Orbital.

基于自旋和轨道的量子传输理论。

基本信息

批准号：
16340097
负责人：
MAEKAWA Sadamichi
金额：
$ 9.92万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340097/
关键词：
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

项目摘要

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.

电子具有内部自由度，即自旋·电荷·轨道，这些自由度产生了材料特性。电子的电荷流动是电流，电子学是基于对电流的控制。基于自旋电流的电子学称为自旋电子学。在过渡金属氧化物中，轨道动力学也是人们所期待的，本项目从电子内部自由度的动力学出发，建立了量子输运理论：1.在非局域自旋霍尔器件中，可以实现自旋电流与电荷电流的转换，并建立了实验组。由于转换是Onsager倒易关系中的一种，所以它是物理学中一个非常基本的概念。2.在由超导体/铁磁体/超导体隧道结组成的器件中，流过两个超导体之间的约瑟夫森电流具有额外的相位π。这被称为π结。3.在几种过渡金属氧化物如Na_xCoO_2中，我们证明了轨道简并导致电子晶格不同于晶体晶格。因此，预期各种新颖的物理性质。在此基础上，我们建立了Na_xCoO_2中的反常霍尔效应和巨热电势。在本项目中，我们从电子的内部自由度出发，研究了各种量子输运现象。