Abstract
Topological states emerge at the boundary of solids as a consequence of the nontrivial topology of the bulk. Recently, theory predicts a topological edge state on single layer transition metal dichalcogenides with 1T’ structure. However, its existence still lacks experimental proof. Here, we report the direct observations of the topological states at the step edge of WTe2 by spectroscopic-imaging scanning tunneling microscopy. A one-dimensional electronic state residing at the step edge of WTe2 is observed, which exhibits remarkable robustness against edge imperfections. First principles calculations rigorously verify the edge state has a topological origin, and its topological nature is unaffected by the presence of the substrate. Our study supports the existence of topological edge states in 1T’-WTe2, which may envision in-depth study of its topological physics and device applications.
Highlights
Topological states emerge at the boundary of solids as a consequence of the nontrivial topology of the bulk
Combining the capability of van der Waals stacking, the transition metal dichalcogenides (TMDs) quantum spin Hall (QSH) insulators provide the advantage of multiple edge conduction channels, which is highly desirable for practical device applications
Step edges of the bulk WTe2 offer the interfaces between the WTe2 layer and the vacuum, which are distinct in electronic topology
Summary
Topological states emerge at the boundary of solids as a consequence of the nontrivial topology of the bulk. In the two-dimensional (2D) topological insulators (TIs)[1, 2], the nontrivial edge state (ES) supports quantum spin Hall (QSH) effect, where the electrons at the edge of the system possess different spins when propagating along opposite directions. Combining the capability of van der Waals (vdW) stacking, the TMD QSH insulators provide the advantage of multiple edge conduction channels, which is highly desirable for practical device applications This stimulates intensive research interests in identifying the topological phases in single layer TMDs, especially how to tune the crystal structure into the 1T’ phase[16,17,18]. Their topological nature is substantiated by theoretical c a c a b b a b d e
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