Quantum Spin Hall Edge States and Interlayer Coupling in Twisted Bilayer WTe<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 35759639.
- Also identified by DOI 10.1021/acs.nanolett.2c00432.
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Abstract
The quantum spin Hall (QSH) effect, characterized by topologically protected spin-polarized edge states, was recently demonstrated in monolayers of the transition metal dichalcogenide (TMD) WTe<sub>2</sub>. However, the robustness of this topological protection remains largely unexplored in van der Waals heterostructures containing one or more layers of a QSH insulator. In this work, we use scanning tunneling microscopy and spectroscopy (STM/STS) to explore the topological nature of twisted bilayer (tBL) WTe<sub>2</sub>. At the tBL edges, we observe the characteristic spectroscopic signatures of the QSH edge states. For small twist angles, a rectangular moiré pattern develops, which results in local modifications of the band structure. Using first-principles calculations, we quantify the interactions in tBL WTe<sub>2</sub> and its topological edge states as a function of interlayer distance and conclude that it is possible to engineer the topology of WTe<sub>2</sub> bilayers via the twist angle as well as interlayer interactions.