Cheng Cai, Sun Jia-Tao, Chen Xiang-Rong, Meng Sheng
Institute of Atomic and Molecular Physics, College of Physical Science and Technology, Sichuan University, Chengdu 610064, China; Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Sci Bull (Beijing). 2018 Jan 30;63(2):85-91. doi: 10.1016/j.scib.2017.12.003. Epub 2017 Dec 6.
The recent discovery of hidden spin polarization emerging in layered materials of specific nonmagnetic crystal is a fascinating phenomenon, though hardly explored yet. Here, we have studied hidden spin textures in layered nonmagnetic 1T-phase transition-metal dichalcogenides MX (M = Zr, Hf; X = S, Se, Te) by using first-principles calculations. Spin-layer locking effect, namely, energy-degenerate opposite spins spatially separated in the top and bottom layer respectively, has been identified. In particular, the hidden spin polarization of β-band can be easily probed, which is strongly affected by the strength of spin-orbit coupling. The hidden spin polarization of ξ-band locating at high symmetry M point (conduction band minimum) has a strong anisotropy. In the bilayer, the hidden spin polarization is preserved at the upmost Se layer, while being suppressed if the ZrSe layer is taken as the symmetry partner. Our results on hidden spin polarization in 1T-phase dichalcogenides, verifiable by spin-resolved and angle-resolved photoemission spectroscopy (ARPES), enrich our understanding of spin physics and provide important clues to search for specific spin polarization in two dimensional materials for spintronic and quantum information applications.
近期在特定非磁性晶体的层状材料中发现的隐藏自旋极化现象是一个引人入胜的现象，尽管目前对此研究甚少。在此，我们通过第一性原理计算研究了层状非磁性1T相过渡金属二硫属化物MX（M = Zr、Hf；X = S、Se、Te）中的隐藏自旋纹理。已识别出自旋层锁定效应，即能量简并的相反自旋分别在顶层和底层空间分离。特别地，可以很容易探测到β带的隐藏自旋极化，其受到自旋轨道耦合强度的强烈影响。位于高对称M点（导带最小值）的ξ带的隐藏自旋极化具有很强的各向异性。在双层结构中，隐藏自旋极化在最上层的Se层得以保留，而如果将ZrSe层作为对称伙伴，则会受到抑制。我们关于1T相二硫属化物中隐藏自旋极化的结果可通过自旋分辨和角分辨光电子能谱（ARPES）进行验证，丰富了我们对自旋物理的理解，并为在二维材料中寻找用于自旋电子学和量子信息应用的特定自旋极化提供了重要线索。
