Quantum spin Hall state in monolayer 1T'-WTe2

• Published in: Nature physics Vol. 13; no. 7; pp. 683 - 687
• Main Authors: Tang, Shujie, Zhang, Chaofan, Wong, Dillon, Pedramrazi, Zahra, Tsai, Hsin-Zon, Jia, Chunjing, Moritz, Brian, Claassen, Martin, Ryu, Hyejin, Kahn, Salman, Jiang, Juan, Yan, Hao, Hashimoto, Makoto, Lu, Donghui, Moore, Robert G., Hwang, Chan-Cuk, Hwang, Choongyu, Hussain, Zahid, Chen, Yulin, Ugeda, Miguel M., Liu, Zhi, Xie, Xiaoming, Devereaux, Thomas P., Crommie, Michael F., Mo, Sung-Kwan, Shen, Zhi-Xun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2017; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 140/146; 639/301/119/2792; 639/766/119/2792; Atomic; Boundary layer; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Crystal structure; Dissipation; Electron spin; Electronic structure; Electrons; Energy gap; Epitaxial growth; First principles; letter; Magnetic fields; Mathematical and Computational Physics; Molecular; Monolayers; Optical and Plasma Physics; Photoelectric emission; Physics; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Quantum theory; Resistance; Scanning tunneling microscopy; Signatures; Spectrum analysis; Spin-orbit interactions; Spinning; Theoretical; Topology; Transition metal compounds; Two dimensional materials
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys4174

A combination of photoemission and scanning tunnelling spectroscopy measurements provide compelling evidence that single layers of 1T'-WTe 2 are a class of quantum spin Hall insulator. A quantum spin Hall (QSH) insulator is a novel two-dimensional quantum state of matter that features quantized Hall conductance in the absence of a magnetic field, resulting from topologically protected dissipationless edge states that bridge the energy gap opened by band inversion and strong spin–orbit coupling 1 , 2 . By investigating the electronic structure of epitaxially grown monolayer 1T'-WTe 2 using angle-resolved photoemission (ARPES) and first-principles calculations, we observe clear signatures of topological band inversion and bandgap opening, which are the hallmarks of a QSH state. Scanning tunnelling microscopy measurements further confirm the correct crystal structure and the existence of a bulk bandgap, and provide evidence for a modified electronic structure near the edge that is consistent with the expectations for a QSH insulator. Our results establish monolayer 1T'-WTe 2 as a new class of QSH insulator with large bandgap in a robust two-dimensional materials family of transition metal dichalcogenides (TMDCs).