Polyakov Andrey, Mohseni Katayoon, Felici Roberto, Tusche Christian, Chen Ying-Jun, Feyer Vitaly, Geck Jochen, Ritschel Tobias, Ernst Arthur, Rubio-Zuazo Juan, Castro German R, Meyerheim Holger L, Parkin Stuart S P
Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany.
Consiglio Nazionale delle Ricerche - SPIN, Via del Politecnico, 1, Roma, 00133, Italy.
Nat Commun. 2022 May 5;13(1):2472. doi: 10.1038/s41467-022-30093-1.
Spin-momentum locking in topological insulators and materials with Rashba-type interactions is an extremely attractive feature for novel spintronic devices and is therefore under intense investigation. Significant efforts are underway to identify new material systems with spin-momentum locking, but also to create heterostructures with new spintronic functionalities. In the present study we address both subjects and investigate a van der Waals-type heterostructure consisting of the topological insulator BiSe and a single Se-Ta-Se triple-layer (TL) of H-type TaSe grown by a method which exploits an interface reaction between the adsorbed metal and selenium. We then show, using surface x-ray diffraction, that the symmetry of the TaSe-like TL is reduced from D to C resulting from a vertical atomic shift of the tantalum atom. Spin- and momentum-resolved photoemission indicates that, owing to the symmetry lowering, the states at the Fermi surface acquire an in-plane spin component forming a surface contour with a helical Rashba-like spin texture, which is coupled to the Dirac cone of the substrate. Our approach provides a route to realize chiral two-dimensional electron systems via interface engineering in van der Waals epitaxy that do not exist in the corresponding bulk materials.
拓扑绝缘体以及具有Rashba型相互作用的材料中的自旋动量锁定,对于新型自旋电子器件来说是极具吸引力的特性,因此正受到广泛研究。目前人们不仅在努力寻找具有自旋动量锁定的新材料体系,还致力于创造具有新自旋电子功能的异质结构。在本研究中,我们探讨了这两个主题,并研究了一种范德华型异质结构,它由拓扑绝缘体BiSe和通过利用吸附金属与硒之间的界面反应生长的H型TaSe的单Se-Ta-Se三层(TL)组成。然后,我们利用表面X射线衍射表明,由于钽原子的垂直原子位移,类TaSe的TL的对称性从D降低到C。自旋和动量分辨光电子能谱表明,由于对称性降低,费米面上的态获得了一个面内自旋分量,形成了具有螺旋状类Rashba自旋纹理的表面轮廓,该纹理与衬底的狄拉克锥耦合。我们的方法提供了一条通过范德华外延中的界面工程来实现手性二维电子系统的途径,而这种系统在相应的体材料中并不存在。