Theoretical study on plea-rival and optical manipulation of magoetization

辩诉竞争与磁化光学操控的理论研究

• 批准号: 16540315
• 负责人: KOHNO Hiroshi
• 金额: $ 2.39万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16540315/
• 关键词: spintronics; magnetic domain wall; spin-transfer effect; spin toroue; spin relaxation; Landau-Lifshitz-Gilbert equation; spin current; magnetic vortex; ゲージ場; Gilbert緩和; 渦対生成; ナノ・モーター; コア反転; 電流に駆動された磁壁の運動; 電流に駆動された磁気渦の運動; スピン移行; ベータ項; ピン止め

(1) The equation of motion of a domain wall under current was derived and analyzed. By taking account of two driving mechanisms (spin transfer and momenturn tinsfer), intrinsic pinning (magnetic anisotropy) and extrinsic pinning (sample inhomogeneity), the depinning mechanisms are classified. The threshold current and domain-wall velocity are obtained for each case, and experimental results are discussed therewith(1) The equation of motion of a domain wall under current was derived and analyzed. By taking account of two driving mechardems (spin transfer and momenturn tinsfer), intrinsic pinning (magnetic anisotropy) and extrinsic pinning (sample inhomogeneity), the depinning mechanisms are classified The threshold current and domain-wall velocity are obtained for each case, and experimental results am discussed therewith(2) Various spin torques that the currents exert on magnetization was microscopically calculated for general magnetization texture. Two theoretical frameworks have been … More developed that can treat electrons' spin-relaxation processes. They are "small-amplitude method", which offers a reliable treatment of non-equilibrium states but is restricted to small-amplitude dynamics, and "gauge-field method", which can treat finite-amplitude dynamics. Simple-minded application of the latter method failed to reproduce the damping but we could overcome this difficulty by a careful treatment of spin-relaxation proceeses. A new physical picture of the damping was obtained as a by-product.(3) Current-driven motion of a magnetic vortex, typically formed in a magnetic disk, was studied theoretically. Resonant excitation of the core, and the reversal of the core magnetization were studied/found by simulations (Prof. Nakatani, UEC) and confirmed experimentally (by Ono group, Kyoto University).(4) Spin-polarized. current in a ferromagnet was known to lead to the softening of spin waves, and eventually to the instability of the uniformly magnetized state. We have found that this instability is followed by the formation of magnetic domain walls (in thin wires) or magnetic vortices (in films or wide wires). The dynamics of two interacting vortices under current was classified according to their vorticity, and polarity which explains well the essential features of the simulation results. Less

(1)推导并分析了电流作用下畴壁的运动方程。考虑到两种驱动机制（自旋转移和动量转移），本征钉扎（磁各向异性）和非本征钉扎（样品的不均匀性），退钉扎机制进行了分类。得到了各种情况下的阈值电流和畴壁速度，并对实验结果进行了讨论。（1）推导并分析了电流作用下畴壁的运动方程。考虑到两种驱动机制（自旋转移和动量转移）：内禀钉扎（磁各向异性）和外禀钉扎（样品不均匀性），对退钉扎机制进行了分类，得到了每种情况下的阈值电流和畴壁速度，并对实验结果进行了讨论。（2）对一般磁化织构，微观计算了电流对磁化作用的各种自旋力矩。两个理论框架， ...更多信息 可以处理电子的自旋弛豫过程。它们是“小振幅方法”，它提供了一个可靠的处理非平衡态，但仅限于小振幅动力学，和“规范场方法”，它可以处理有限振幅动力学。简单地应用后一种方法不能再现阻尼，但我们可以通过仔细处理自旋弛豫过程来克服这一困难。作为副产品，获得了阻尼的新物理图像。(3)本文从理论上研究了磁涡旋在电流驱动下的运动。通过模拟（Nakatani教授，UEC）研究/发现了芯的共振激发和芯磁化的反转，并通过实验（由Ono group，京都大学）进行了确认。(4)自旋极化众所周知，铁磁体中的电流会导致自旋波的软化，并最终导致均匀磁化状态的不稳定性。我们已经发现，这种不稳定性之后形成磁畴壁（在细线）或磁涡旋（在薄膜或宽线）。根据涡度和极性对流场中两个相互作用涡的动力学进行了分类，很好地解释了模拟结果的本质特征。少

项目成果

Theory of current-driven domain wall dynamics

电流驱动畴壁动力学理论

• 发表时间: 2007
• 期刊: Journal of Physics D : Applied Physics 40巻
• 作者: 多々良 源;他
• 通讯作者: 他

Gauge Field Formulation of Adiabatic Spin Torques

• DOI: 10.1143/jpsj.76.063710
• 发表时间: 2007-03
• 期刊: Journal of the Physical Society of Japan
• 影响因子: 1.7
• 作者: H. Kohno;J. Shibata

Nucleation and dynamics of magnetic vortices under spin-polarized current

• DOI: 10.1103/physrevb.77.014439
• 发表时间: 2008-01
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Y. Nakatani;J. Shibata;G. Tatara;H. Kohno;A. Thiaville;J. Miltat

Effects of spin-orbit coupling on spin torque

自旋轨道耦合对自旋扭矩的影响

• 发表时间: 2008
• 作者: S.;Kawabata
• 通讯作者: Kawabata

Spintronic Materials and Technology(Chapter 10, pp. 225-241)

自旋电子材料与技术（第10章，第225-241页）

• 发表时间: 2006
• 作者: Satoru Nakatsuji;Yusuke Nambu;Hiroshi Tonomura;Osamu Sakai;Seth Jonas;Collin Broholm;Hirokazu Tsunetsugu;Yiming Qiu;Yoshiteru Maeno;河野 浩
• 通讯作者: 河野 浩