Lu Qiangsheng, Cook Jacob, Zhang Xiaoqian, Chen Kyle Y, Snyder Matthew, Nguyen Duy Tung, Reddy P V Sreenivasa, Qin Bingchao, Zhan Shaoping, Zhao Li-Dong, Kowalczyk Pawel J, Brown Simon A, Chiang Tai-Chang, Yang Shengyuan A, Chang Tay-Rong, Bian Guang
Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA.
Rock Bridge High School, Columbia, MO, 65203, USA.
Nat Commun. 2022 Aug 6;13(1):4603. doi: 10.1038/s41467-022-32327-8.
Two-dimensional (2D) Dirac states with linear dispersion have been observed in graphene and on the surface of topological insulators. 2D Dirac states discovered so far are exclusively pinned at high-symmetry points of the Brillouin zone, for example, surface Dirac states at [Formula: see text] in topological insulators BiSe(Te) and Dirac cones at K and [Formula: see text] points in graphene. The low-energy dispersion of those Dirac states are isotropic due to the constraints of crystal symmetries. In this work, we report the observation of novel 2D Dirac states in antimony atomic layers with phosphorene structure. The Dirac states in the antimony films are located at generic momentum points. This unpinned nature enables versatile ways such as lattice strains to control the locations of the Dirac points in momentum space. In addition, dispersions around the unpinned Dirac points are highly anisotropic due to the reduced symmetry of generic momentum points. The exotic properties of unpinned Dirac states make antimony atomic layers a new type of 2D Dirac semimetals that are distinct from graphene.
在石墨烯和拓扑绝缘体表面已观测到具有线性色散的二维（2D）狄拉克态。迄今为止发现的二维狄拉克态仅固定在布里渊区的高对称点上，例如，拓扑绝缘体BiSe(Te)中[公式：见原文]处的表面狄拉克态以及石墨烯中K点和[公式：见原文]点处的狄拉克锥。由于晶体对称性的限制，这些狄拉克态的低能色散是各向同性的。在这项工作中，我们报告了在具有磷烯结构的锑原子层中观测到新型二维狄拉克态。锑薄膜中的狄拉克态位于一般动量点处。这种非固定性质使得诸如晶格应变等多种方式能够控制动量空间中狄拉克点的位置。此外，由于一般动量点的对称性降低，非固定狄拉克点周围的色散具有高度各向异性。非固定狄拉克态的奇异性质使锑原子层成为一种不同于石墨烯的新型二维狄拉克半金属。
