摘要
The topological edge states of two-dimensional topological insulators with large energy gaps furnish ideal conduction channels for dissipationless current transport. Transition metal tellurides XTe5X=Zr, Hf) are theoretically predicted to be large-gap two-dimensional topological insulators, and the experimental observations of their bulk insulating gap and in-gap edge states have been reported, but the topological nature of these edge states still remains to be further elucidated. Here, we report our low-temperature scanning tunneling microscopy/spectroscopy study on single crystals of HfTe5. We demonstrate a full energy gap of ~80 meV near the Fermi level on the surface monolayer of HfTe5 and that such an insulating energy gap gets filled with finite energy states when measured at the monolayer step edges. Remarkably, such states are absent at the edges of a narrow monolayer strip of one-unit-cell in width but persist at both step edges of a unit-cell wide monolayer groove. These experimental observations strongly indicate that the edge states of HfTe5 monolayers are not trivially caused by translational symmetry breaking, instead they are topological in nature protected by the 2 D nontrivial bulk properties.
The topological edge states of two-dimensional topological insulators with large energy gaps furnish ideal conduction channels for dissipationless current transport. Transition metal tellurides XTe5X=Zr, Hf) are theoretically predicted to be large-gap two-dimensional topological insulators, and the experimental observations of their bulk insulating gap and in-gap edge states have been reported, but the topological nature of these edge states still remains to be further elucidated. Here, we report our low-temperature scanning tunneling microscopy/spectroscopy study on single crystals of HfTe5. We demonstrate a full energy gap of ～80 meV near the Fermi level on the surface monolayer of HfTe5 and that such an insulating energy gap gets filled with finite energy states when measured at the monolayer step edges. Remarkably, such states are absent at the edges of a narrow monolayer strip of one-unit-cell in width but persist at both step edges of a unit-cell wide monolayer groove. These experimental observations strongly indicate that the edge states of HfTe5 monolayers are not trivially caused by translational symmetry breaking, instead they are topological in nature protected by the 2 D nontrivial bulk properties.
作者
Rui-Zhe Liu
Xiong Huang
Ling-Xiao Zhao
Li-Min Liu
Jia-Xin Yin
Rui Wu
Gen-Fu Chen
Zi-Qiang Wang
Shuheng HPan
刘睿哲;黄雄;赵凌霄;刘立民;殷嘉鑫;武睿;陈根富;汪自强;潘庶亨(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190;Physical Science Laboratory,Huairou National Comprehensive Science Center,Huairou,Beijing 101400;School of Physics,University of Chinese Academy of Sciences,Beijing 100190;Laboratory for Topological Quantum Matter and Advanced Spectroscopy(B7),Department of Physics,Princeton University,Princeton,NJ,USA;Songshan Lake Material Laboratory,Dongguan 523808;Department of Physics,Boston College,Chestnut Hill,Massachusetts 02467,USA;CAS Center for Excellence in Topological Quantum Computation,University of Chinese Academy of Sciences,Beijing 100190)
基金
Supported by the Chinese Academy of Sciences
the National Natural Science Foundation of China under Grant No 11227903
the BM-STC under Grant No Z181100004218007
the National Basic Research Program of China under Grant Nos 2015CB921300and 2015CB921304
National Key R&D Program of China under Grant No 2017YFA0302903
the Strategic Priority Research Program B of the Chinese Academy of Sciences under Grant Nos XDB04040300 and XDB07000000
Beijing Municipal Science&Technology Commission(Z181100004218007)
