Theory of Quantum Transport based on Spin and Orbital.

基于自旋和轨道的量子传输理论。

• 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

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，自旋·电荷·轨道，这些自由度产生了材料特性。电子的电荷流动就是电流，而电子学是基于电流的控制。基于自旋电流的电子学称为自旋。 -电子学。轨道动力学也被期望在过渡金属氧化物中。在这个项目中，从电子这些内部自由度的动力学开始构建了量子输运理论。1.结果表明，自旋电流和充电电流可表示为由于转换是Onsager倒数关系之一，因此它是物理学中非常基本的概念。2.在由超导体/铁磁体/超导体隧道结组成的装置中，在两个超导体之间流动的约瑟夫森电流具有额外的相位，π，这被称为π结我们提出具有π结的超导环可以用作量子计算装置。 （量子位）不施加磁场。3.在Na_xCoO_2等几种过渡金属氧化物中，我们已经证明轨道简并性导致电子晶格与晶体晶格不同，从而有望获得多种新颖的物理性质。基于该理论，我们公式化了在Na_xCoO_2中观察到的反常霍尔效应和巨热电势。在这个项目中，我们从电子的内部自由度开始研究各种量子输运现象。

项目成果

Superconducting π qubit with three Josephson junctions.

具有三个约瑟夫森结的超导 π 量子位。

• 发表时间: 2006
• 期刊: Appl. Phys. Lett. 88
• 作者: T.Yamashita;S.Takahashi;S.Maekawa
• 通讯作者: S.Maekawa

Momentum Dependence of Charge Excitations in the Electron-Doped Superconductor Nd_<1.85>Ce_<0.15>CuO_4 : a Resonant Inelastic X-ray Scattering Study

电子掺杂超导体Nd_<1.85>Ce_<0.15>CuO_4中电荷激发的动量依赖性：共振非弹性X射线散射研究

• 发表时间: 2005
• 期刊: Phys.Rev.Lett. 94
• 作者: K.Ishii K.Tsutsui;Y.Endoh;T.Tohyama;S.Maekawa;M.Hoesch;K.Kuzushita;M.Tsubota;T.Inami;et al.
• 通讯作者: et al.

Fermi surface splittings in multilayered high-Tc cuprates

多层高温铜酸盐中的费米表面分裂

• 发表时间: 2006
• 期刊: Physica C 445-448
• 作者: M.Mori;T.Tohyama;S.Maekawa
• 通讯作者: S.Maekawa

Many-body effects in nanospintronics devices.

纳米自旋电子器件中的多体效应。

• 发表时间: 2004
• 期刊: J.Mag.Soc.Jpn. 28(11)
• 作者: Y.Utsumi;J.Martinek;P.Bruno;J.Barnas;S.Maekawa
• 通讯作者: S.Maekawa

Andreev reflection in ferromagnet/superconductor/ferromagnet junctions

铁磁体/超导体/铁磁体结中的安德烈夫反射

• 发表时间: 2004
• 期刊: J. Magn. Magn. Mater. 272-276
• 作者: T.Watanabe;H.Yokoyama;Y.Tanaka;J.Inoue;M.Ogata;S.Takahashi;T.Yamashita;S.Takahashi;T.Yamashita;H.Imamura;T.Yamashita;S.E.Barnes;S.Kaji;T.Yamashita;T.Yamashita;S.Kaji;T.Yamashita
• 通讯作者: T.Yamashita