Quantum Spin Hall Edge States and Interlayer Coupling in Twisted Bilayer WTe 2

作者：Felix Lüpke, Dacen Waters, Anh Pham, Jiaqiang Yan, David Mandrus, Panchapakesan Ganesh, Benjamin Hunt · 发表于：Nano Letters · 年份：2022 · DOI：10.1021/acs.nanolett.2c00432 · 被引用次数：14 · 研究领域：Topological Materials and Phenomena、Graphene research and applications、2D Materials and Applications

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 2 . 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 2 . 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 2 and its topological edge states as a function of interlayer distance and conclude that it is possible to engineer the topology of WTe 2 bilayers via the twist angle as well as interlayer interactions.