Observation of topological states residing at step edges of WTe2

TL;DR

This study provides experimental evidence of topological edge states at step edges of WTe2, confirming theoretical predictions and highlighting potential for topological physics research and device applications.

Contribution

First direct observation of topological edge states in WTe2 using spectroscopic-imaging STM, verifying their topological origin through first principles calculations.

Findings

Detected 1D electronic states at WTe2 step edges

Confirmed topological nature of edge states via calculations

Edge states are unaffected by substrate presence

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 has a spatial extension of about 2.5 nm. 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.