Direct Visualization of 2D Topological Insulator in Single-layer 1T'-WTe2

TL;DR

This study demonstrates the growth and characterization of single-layer 1T'-WTe2, revealing topological edge states and a bulk band gap, indicating its potential as a 2D topological insulator platform.

Contribution

It provides direct experimental evidence of topological edge states in single-layer WTe2 grown by MBE, highlighting its semiconducting behavior and topological properties.

Findings

Existence of topological edge states at the periphery of WTe2 islands

Observation of a bulk band gap and semiconducting behavior at low temperature

Potential of single-layer WTe2 as a 2D topological insulator platform

Abstract

We grow nearly freestanding single-layer 1T'-WTe2 on graphitized 6H-SiC(0001) by using molecular beam epitaxy (MBE), and characterize its electronic structure with scanning tunneling microscopy / spectroscopy (STM/STS). We demonstrate the existence of topological edge states at the periphery of single-layer WTe2 islands. Surprisingly, we also find a band gap in the bulk and the semiconducting behaviors of the single-layer WTe2 at low temperature, which is likely resulted from an incommensurate charge density wave (CDW) transition. The realization of two-dimensional topological insulators (2D TIs) in single-layer transition metal dichalcogenide (TMD) thus provides a promising platform for further exploration of the 2D TIs' physics and related applications.