Liu Bing, Liu Jian, Miao Guangyao, Xue Siwei, Zhang Shuyuan, Liu Lixia, Huang Xiaochun, Zhu Xuetao, Meng Sheng, Guo Jiandong, Liu Miao, Wang Weihua
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China.
School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China.
J Phys Chem Lett. 2019 Apr 18;10(8):1866-1871. doi: 10.1021/acs.jpclett.9b00339. Epub 2019 Apr 4.
The intriguing properties of graphene have inspired the pursuit of two-dimensional materials with honeycomb structure. Here we achieved the synthesis of a monolayer transition-metal monochalcogenide AgTe on Ag(111) by tellurization of the substrate. High-resolution scanning tunneling microscopy, combined with low-energy electron diffraction, angle-resolved photoemission spectroscopy, and density functional theory calculations, demonstrates the planar honeycomb structure of AgTe. The first-principles calculations further predict that, protected by the in-plane mirror reflection symmetry, there are two Dirac node-line fermions existing in the free-standing AgTe when spin-orbit coupling (SOC) is ignored. In fact, the SOC leads to the gap opening, resulting in the emergence of the topologically nontrivial quantum spin Hall edge state. Importantly, our experiments evidence the chemical stability of the monolayer AgTe in ambient conditions, making it possible to study AgTe by more ex situ measurements and even to utilize AgTe in future electronic devices.
石墨烯的有趣特性激发了人们对具有蜂窝结构的二维材料的探索。在此，我们通过对银（111）衬底进行碲化处理，成功合成了单层过渡金属硫族化合物AgTe。高分辨率扫描隧道显微镜结合低能电子衍射、角分辨光电子能谱和密度泛函理论计算，证实了AgTe的平面蜂窝结构。第一性原理计算进一步预测，在忽略自旋轨道耦合（SOC）的情况下，由于面内镜像反射对称性的保护，独立的AgTe中存在两个狄拉克节线费米子。实际上，SOC导致能隙打开，从而出现拓扑非平凡的量子自旋霍尔边缘态。重要的是，我们的实验证明了单层AgTe在环境条件下的化学稳定性，这使得通过更多的非原位测量来研究AgTe甚至在未来的电子器件中利用AgTe成为可能。
