Kohda Makoto, Okayasu Takanori, Nitta Junsaku
Department of Materials Science, Tohoku University, 6-6-02 Aramaki-Aza Aoba, Aoba-ku, Sendai, 980-8579, Japan.
Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
Sci Rep. 2019 Feb 13;9(1):1909. doi: 10.1038/s41598-018-37967-9.
Spin-momentum locking, which constrains spin orientation perpendicular to electron momentum, is attracting considerable interest for exploring various spin functionalities in semiconductors and topological materials. Efficient spin generation and spin detection have been demonstrated using the induced helical spin texture. Nevertheless, spin manipulation by spin-momentum locking remains a missing piece because, once bias voltage is applied to induce the current flow, the spin orientation must be locked by the electron momentum direction, thereby rendering spin phase control difficult. Herein, we demonstrate the spin-momentum locking-induced spin manipulation for ballistic electrons in a strong Rashba two-dimensional system. Electron spin rotates in a circular orbital motion for ballistically moving electrons, although spin orientation is locked towards the spin-orbit field because of the helical spin texture. This fact demonstrates spin manipulation by control of the electron orbital motion and reveals potential effects of the orbital degree of freedom on the spin phase for future spintronic and topological devices and for the processing of quantum information.
自旋动量锁定将自旋方向限制在垂直于电子动量的方向，在探索半导体和拓扑材料中的各种自旋功能方面引起了广泛关注。利用诱导的螺旋自旋纹理已证明了高效的自旋产生和自旋检测。然而，通过自旋动量锁定进行自旋操纵仍然是一个缺失的环节，因为一旦施加偏置电压以诱导电流流动，自旋方向就必须由电子动量方向锁定，从而使得自旋相位控制变得困难。在此，我们展示了在强Rashba二维系统中弹道电子的自旋动量锁定诱导的自旋操纵。对于弹道移动的电子，电子自旋以圆周轨道运动旋转，尽管由于螺旋自旋纹理，自旋方向被锁定在自旋轨道场方向。这一事实证明了通过控制电子轨道运动来进行自旋操纵，并揭示了轨道自由度对未来自旋电子学和拓扑器件以及量子信息处理中的自旋相位的潜在影响。
