Design of Electron-Spintronics devices

电子自旋电子器件的设计

• 批准号: 14076204
• 负责人: IMAMURA Hiroshi
• 金额: $ 12.42万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14076204/
• 关键词: quantum dot; quantum wire; quantum; information; Rashba spin-orbit interaction; spin Hall effect; tunnel magnetoresistance; Coulomb blockade; polarization; 量子情報転写; スピン流; 磁壁; スピントロニクス; アンドレーエフ反射; スピントランジスタ; 半導体人工分子; ナノ粒子; RKKY相互作用; デバイスデザ

Recent progress in nano-fabrication technology enables us to confine electrons in nano-structures such quantum dots or quantum wires. Our objective is to design the nano-electronspintoronics devices where the spin degrees of freedom of electrons play an important role. Our main results are listed below.1. We studied the spin configuration of the ground state of an artificial molecule consisting of semiconductor quantum dots and quantum wires. We theoretically study the RKKY interaction between localized spins embedded in a 1D-or 2DEG with Rashba spin-orbit coupling. We also study the spin-configuration of linear and ring-shaped artificial molecules consisting localized spins coupled via the twisted RKKY interaction. We find that the squaremorm of the total spin of an artificial molecule oscillates with the twist angle 0 and has maxima at 0 = an odd integer times II. The square-norm of the total spin of the ring-shaped artificial molecules change drastically at certain values of 0 where … More the lowest two energy levels cross each other.2. We analyzed the fidelity of the quantum state transfer (QST) from a photon-polarization qubit to an electron-spin-polarization qubit in a semiconductor quantum dot, with special attention to the exchange interaction between the electron and the simultaneously created hole. In order to realize a high-fidelity QST we had to separate the electron and hole as soon as possible, since the electron-hole exchange interaction modifies the orientation of the electron spin. Thus, we propose a double-dot structure to separate the electron and hole quickly and show that the fidelity of the QST can reach as high as 0.996 if the resonant tunneling condition is satisfied.3. We analyzed the experimentally observed TMR ratio of Co nanoparticles in the Coulomb blockade regime and found that the spin relaxation time in nano-partides is highly enhanced in comparison with that in the bulk. 4. We studied theoretically the spin transport in a nonmagnetic metal connected to ferromagnetic injector and detector electrodes. We derived a general expression for the spin accumulation signal which covers from the metallic to the tunneling regime. This enables us to discuss reoent controversy on spin injection and detection experiments. Extending the result to a superconducting device, we found that the spin accumulation signal was strongly enhanced by opening of the superconducting gap since a gapped superconductor was a low carrier system for spin transport but not for charge. The enhancement is also expected in semiconductor devices. Less

纳米制造技术的最新进展使我们能够将电子限制在量子点或量子线等纳米结构中。我们的目标是设计纳米电子自旋电子学器件，其中电子的自旋自由度发挥重要作用。我们的主要结果如下所示。1.研究了由半导体量子点和量子线组成的人工分子的基态自旋构型。我们从理论上研究了具有Rashba自旋轨道耦合的一维或二维电子气中局域自旋之间的RKKY相互作用。我们还研究了线性和环形人工分子的自旋配置，包括通过扭曲的RKKY相互作用耦合的本地化自旋。我们发现，人工分子的总自旋的平方振荡与扭转角0，并在0 =一个奇数倍II有最大值。环形人造分子的总自旋的平方范数在0的某些值处急剧变化，其中 ...更多信息 最低的两个能级相互交叉。我们分析了半导体量子点中从光子极化量子比特到电子自旋极化量子比特的量子态转移（QST）的保真度，特别关注了电子和同时产生的空穴之间的交换相互作用.为了实现高保真的QST，我们必须尽快分离电子和空穴，因为电子-空穴交换相互作用改变了电子自旋的取向。因此，我们提出了一种双点结构来快速分离电子和空穴，并证明了在满足共振隧穿条件的情况下，QST的保真度可以达到0.996.我们分析了实验观察到的钴纳米粒子在库仑阻塞制度的TMR比，并发现在纳米粒子的自旋弛豫时间是大大增强，在体相比较。4.本文从理论上研究了与铁磁注入电极和检测电极相连的双金属中的自旋输运。我们导出了从金属态到隧穿态的自旋积累信号的一般表达式。这使我们能够讨论自旋注入和探测实验中的争议。将结果推广到超导器件，我们发现，自旋积累信号强烈增强的超导间隙的开放，因为带隙的超导体是一个低载流子系统的自旋输运，但不是电荷。在半导体器件中也预期这种增强。少

项目成果

Vortex nucreation and annihilation in superconducting Corbino disks

超导 Corbino 盘中的涡旋成核和湮灭

• 发表时间: 2005
• 期刊: Physica C (発表予定)
• 作者: M.Hayashi;et al.
• 通讯作者: et al.

Enhanced spin accumulation and novel magnetotransport in nanoparticles

• DOI: 10.1038/nmat1278
• 发表时间: 2004-12
• 期刊: Nature Materials
• 影响因子: 41.2
• 作者: K. Yakushiji;F. Ernult;H. Imamura;K. Yamane;S. Mitani;K. Takanashi;S. Takahashi;S. Maekawa;H. Fujimori

"Concepts in Spin Electronics", Chapter 9

“自旋电子学中的概念”，第 9 章

• 发表时间: 2006
• 期刊: Oxford University Press
• 作者: H.Imamura;S.Takahashi;S.Maekawa
• 通讯作者: S.Maekawa

Indirect Exchange Interaction between two Quantum Dots in an Aharc nov-Bohm Ring

Aharc nov-Bohm 环中两个量子点之间的间接交换相互作用

• 发表时间: 2004
• 期刊: Physical Review B 69
• 作者: Y.Utsumi;et al.
• 通讯作者: et al.

S.Maekawa, S.Takahashi, H.Imamura: "Spin injection into Superconductors"JOURNAL OF PHYSICS D-APPLIED PHYSICS. 35・19. 2452-2456 (2002)

S.Maekawa、S.Takahashi、H.Imamura：“自旋注入超导体”物理学 D-应用物理学杂志 35・19（2002 年）。