Observation of Topologically Protected States at Crystalline Phase Boundaries in Single-layer WSe2

Abstract

Transition metal dichalcogenide (TMD) materials are unique in the wide variety of structural and electronic phases they exhibit in the two-dimensional (2D) single-layer limit. Here we show how such polymorphic flexibility can be used to achieve topological states at highly ordered phase boundaries in a new quantum spin Hall insulator (QSHI), 1T'-WSe2. We observe helical states at the crystallographically-aligned interface between quantum a spin Hall insulating domain of 1T'-WSe2 and a semiconducting domain of 1H-WSe2 in contiguous single layers grown using molecular beam epitaxy (MBE). The QSHI nature of single-layer 1T'-WSe2 was verified using ARPES to determine band inversion around a 120 meV energy gap, as well as STM spectroscopy to directly image helical edge-state formation. Using this new edge-state geometry we are able to directly confirm the predicted penetration depth of a helical interface state into the 2D bulk of a QSHI for a well-specified crystallographic direction. The clean, well-ordered topological/trivial interfaces observed here create new opportunities for testing predictions of the microscopic behavior of topologically protected boundary states without the complication of structural disorder.

arXiv commenthttps://www.nature.com/articles/s41467-018-05672-w

References in corpus (25)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Energy Band Gap Engineering of Graphene Nanoribbons
• WannierTools: An open-source software package for novel topological materials
• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Bismuthene on a SiC Substrate: A Candidate for a New High-Temperature Quantum Spin Hall Paradigm
• Evidence for Helical Edge Modes in Inverted InAs/GaSb Quantum Wells
• Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2
• Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
• Characterization of collective ground states in single-layer NbSe2
• Quantum Spin Hall Effect and Enhanced Magnetic Response by Spin-Orbit Coupling
• Edge conduction in monolayer WTe2
• Giant Phonon-induced Conductance in Scanning Tunneling Spectroscopy of Gate-tunable Graphene
• One-dimensional Topological Edge States of Bismuth Bilayers
• Stable nontrivial Z2 topology in ultrathin Bi (111) films: a first-principles study
• Angle Dependent Van Hove Singularities in Slightly Twisted Graphene Bilayer
• Electronic Structure, Surface Doping, and Optical Response in Epitaxial WSe2 Thin Films
• Fully gapped topological surface states in Bi${}_2$Se${}_3$ films induced by a d-wave high-temperature superconductor
• Direct Visualization of 2D Topological Insulator in Single-layer 1T'-WTe2
• Sub-nm wide electron channels protected by topology
• Robust spin-polarized midgap states at step edges of topological crystalline insulators
• Understanding topological phase transition in transition metal dichalcogenides
• Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T'-WTe${}_2$
• Growth, stabilization and conversion of semi-metallic and semiconducting phases of MoTe2 monolayer by molecular-beam epitaxy

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