Growth and Characterization of single-layer 1T’-WTe2

Title: Growth and Characterization of single-layer 1T’-WTe2

Speaker: Li Shaochun

Location: Room 101, Physical science Building

Time: 15:00-16:00p.m. Dec 11th, 2018

Abstract: The discovery of topological insulators (TIs) has drawn intense attention due to the intriguing properties of this new type of quantum matter. Single-layer 1T’-WTe2 has been recently predicted as the candidate of quantum spin Hall material. Even though experimental progress has been made, the band structure of 1T’-WTe2 is still not well determined. In this presentation, we systematically discuss the growth and characterization of 1T’-WTe2 film. By using the epitaxial graphene /SiC(0001) as the substrate, we found 1T’-WTe2 initially prefers the single-layer growth mode, followed by the nucleation of the second layer on top of the first layer. Scanning tunneling microscopy was applied to investigate the electronic structure of single-layer 1T’-WTe2 as well as its topological edge states. In contrast to the ARPES results, we find the 1T’-WTe2 holds a semimetal-like band structure and the existence of Coulomb gap at the Fermi energy. The Coulomb gap efficiently suppresses the bulk state with the edge state unchanged, thus facilitating the observation of quantum spin Hall effect in this system.