Abstract
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 ∼100 meV 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.Received 31 December 2015DOI:https://doi.org/10.1103/PhysRevX.6.021017This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical Society
Highlights
A topological insulator (TI) is a novel state of matter characterized by an energy gap in the bulk and gapless Dirac fermionic states connecting the valence and conduction bands on the boundary
By using scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS) and angle-resolved photoemission spectroscopy (ARPES), we systematically investigate the electronic states on the surface and at a monolayer step edge of ZrTe5 crystals
To clarify the origin of the energy gap observed in the STS, we perform systematic ARPES measurements on the (010) surface
Summary
A topological insulator (TI) is a novel state of matter characterized by an energy gap in the bulk and gapless Dirac fermionic states connecting the valence and conduction bands on the boundary. Backscattering is prohibited as long as time-reversal symmetry is not broken, leading to dissipationless transport edge channels and quantum spin Hall (QSH) effect [1,2] These exotic properties suggest tantalizing possibilities in electronic device applications. An alternative way to achieve 2D TIs with topological edge states is to utilize the step edges on the surface of a cleaved single crystal Such topological edge states have been observed on the surfaces of Bi and Bi14Rh3I9 crystals [22,23], but still with an undesired finite DOS inside the energy gap in the area away from the step edges. The high-resolution STS spectrum shows no DOS inside the entire energy gap on the surface area far away from the step edge, indicating that the bulk material of ZrTe5 is in a weak TI phase. Such edge states are well reproduced by our single-layer ribbon calculations that show topologically nontrivial Diraclike edge states exist inside the large energy gap
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
