Quantum spin Hall edge states and interlayer coupling in twisted-bilayer WTe$_2$
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arXiv
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| Autores principales: | , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2020
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| author | Lüpke, Felix Waters, Dacen Pham, Anh D. Yan, Jiaqiang Mandrus, David G. Ganesh, Panchapakesan Hunt, Benjamin M. |
| author_facet | Lüpke, Felix Waters, Dacen Pham, Anh D. Yan, Jiaqiang Mandrus, David G. Ganesh, Panchapakesan Hunt, Benjamin M. |
| contents | 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$_2$ which is produce from folded monolayers, as well as, tear-and-stack fabrication. At the tBL bilayer edge, we observe the characteristic spectroscopic signature of the QSH edge state that is absent in topologically trivial as-grown bilayer. 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 function of interlayer distance and conclude that it is possible to tune the topology of WTe$_2$ bilayers via the twist angle as well as interlayer interactions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2010_13699 |
| institution | arXiv |
| publishDate | 2020 |
| record_format | arxiv |
| spellingShingle | Quantum spin Hall edge states and interlayer coupling in twisted-bilayer WTe$_2$ Lüpke, Felix Waters, Dacen Pham, Anh D. Yan, Jiaqiang Mandrus, David G. Ganesh, Panchapakesan Hunt, Benjamin M. Mesoscale and Nanoscale Physics 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$_2$ which is produce from folded monolayers, as well as, tear-and-stack fabrication. At the tBL bilayer edge, we observe the characteristic spectroscopic signature of the QSH edge state that is absent in topologically trivial as-grown bilayer. 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 function of interlayer distance and conclude that it is possible to tune the topology of WTe$_2$ bilayers via the twist angle as well as interlayer interactions. |
| title | Quantum spin Hall edge states and interlayer coupling in twisted-bilayer WTe$_2$ |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2010.13699 |