Evidence for Topological Edge States in a Large Energy Gap near the Step Edges on the Surface of ZrTe5

• Published in: Physical review. X 2016-05, Vol.6 (2)
• Main Authors: R. Wu, J.-Z. Ma, S.-M. Nie, L.-X. Zhao, Huang, X, J.-X. Yin, B.-B. Fu, Richard, P, G.-F. Chen, Fang, Z, Dai, X, H.-M. Weng, Qian, T, Ding, H, Pan, S H
• Format: Article
• Language: English
• Subjects: Crystals; Density of states; Electromagnetism; Electron spin; Electrons; Energy dissipation; Energy gap; First principles; High temperature; Mathematical analysis; Microscopy; Monolayers; Photoelectric emission; Photoelectron spectroscopy; Quantum Hall effect; Resistance; Scanning tunneling microscopy; Spectrum analysis; Spintronics; Topological insulators
• ISSN: 2160-3308
• DOI: 10.1103/PhysRevX.6.021017

Two-dimensional topological insulators with a large bulk band gap are promising for experimental studies of quantum spin Hall effect and for spintronic device applications. Despite considerable theoretical efforts in predicting large-gap two-dimensional topological insulator candidates, none of them have been experimentally demonstrated to have a full gap, which is crucial for quantum spin Hall effect. Here, by combining scanning tunneling microscopy/spectroscopy and angle-resolved photoemission spectroscopy, we reveal that ZrTe5 crystal hosts a large full gap of ∼100meV on the surface and a nearly constant density of states within the entire gap at the monolayer step edge. These features are well reproduced by our first-principles calculations, which point to the topologically nontrivial nature of the edge states.