Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany.
Phys Rev Lett. 2012 May 18;108(20):207202. doi: 10.1103/PhysRevLett.108.207202. Epub 2012 May 14.
When a foreign atom is placed on a surface of a metal, the surrounding sea of electrons responds by screening the additional charge leading to oscillations or ripples. On surfaces, those electrons are sometimes confined to two-dimensional surface states, whose spin-degeneracy is lifted due to the Rashba effect arising from the spin-orbit interaction of electrons and the inversion asymmetric environment. It is believed that at least for a single adatom scanning tunneling microscopy measurements are insensitive to the Rashba splitting; i.e., no signatures in the charge oscillations will be observed. Resting on scattering theory, we demonstrate that, if magnetic, one single adatom is enough to visualize the presence of the Rashba effect in terms of an induced spin magnetization of the surrounding electrons exhibiting a twisted spin texture described as superposition of two Skyrmionic waves of opposite chirality.
当一个外来原子被放置在金属表面上时,周围的电子海会通过屏蔽额外的电荷来做出响应,从而导致电子的振荡或波动。在表面上,这些电子有时会被限制在二维表面态中,由于电子的自旋轨道相互作用和反转不对称环境引起的 Rashba 效应,其自旋简并度会被解除。人们相信,至少对于单个吸附原子来说,扫描隧道显微镜测量对 Rashba 劈裂是不敏感的;也就是说,在电荷振荡中不会观察到任何特征。基于散射理论,我们证明了,如果是磁性的,单个吸附原子就足以通过周围电子的感应自旋磁化来可视化 Rashba 效应的存在,这种感应自旋磁化表现为两个具有相反手性的 Skyrmionic 波的叠加,呈现出扭曲的自旋结构。