Xu Yong-Jie, Cao Guohua, Li Qi-Yuan, Xue Cheng-Long, Zhao Wei-Min, Wang Qi-Wei, Dou Li-Guo, Du Xuan, Meng Yu-Xin, Wang Yuan-Kun, Gao Yu-Hang, Jia Zhen-Yu, Li Wei, Ji Lianlian, Li Fang-Sen, Zhang Zhenyu, Cui Ping, Xing Dingyu, Li Shao-Chun
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China.
International Center for Quantum Design of Functional Materials (ICQD), University of Science and Technology of China, Hefei, China.
Nat Commun. 2024 Jun 5;15(1):4784. doi: 10.1038/s41467-024-49197-x.
Two-dimensional topological insulators hosting the quantum spin Hall effect have application potential in dissipationless electronics. To observe the quantum spin Hall effect at elevated temperatures, a wide band gap is indispensable to efficiently suppress bulk conduction. Yet, most candidate materials exhibit narrow or even negative band gaps. Here, via elegant control of van der Waals epitaxy, we have successfully grown monolayer ZrTe on a bilayer graphene/SiC substrate. The epitaxial ZrTe monolayer crystalizes in two allotrope isomers with different intralayer alignments of ZrTe prisms. Our scanning tunneling microscopy/spectroscopy characterization unveils an intrinsic full band gap as large as 254 meV and one-dimensional edge states localized along the periphery of the ZrTe monolayer. First-principles calculations further confirm that the large band gap originates from strong spin-orbit coupling, and the edge states are topologically nontrivial. These findings thus provide a highly desirable material platform for the exploration of the high-temperature quantum spin Hall effect.
具有量子自旋霍尔效应的二维拓扑绝缘体在无耗散电子学中具有应用潜力。为了在高温下观测量子自旋霍尔效应，宽带隙对于有效抑制体传导是必不可少的。然而，大多数候选材料表现出窄带隙甚至负带隙。在此，通过对范德华外延的精确控制，我们成功地在双层石墨烯/碳化硅衬底上生长了单层ZrTe。外延ZrTe单层以两种具有不同ZrTe棱柱层内排列的同素异形体异构体形式结晶。我们的扫描隧道显微镜/光谱表征揭示了一个高达254 meV的本征全带隙以及沿ZrTe单层边缘局域化的一维边缘态。第一性原理计算进一步证实，大带隙源于强自旋轨道耦合，且边缘态具有非平凡拓扑性质。因此，这些发现为探索高温量子自旋霍尔效应提供了一个非常理想的材料平台。
