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Van der Waals heterostructures allow the combination of different material properties, e.g. non-trivial topology and superconductivity in order to create a topological superconducting state. In my talk, I demonstrate a novel dry-transfer flip technique which allows to place atomically-thin layers of WTe₂, a quantum spin hall system, on NbSe₂, a van der Waals superconductor. Using scanning tunneling microscopy and spectroscopy (STM/STS), we demonstrate atomically clean surfaces and interfaces and the presence of a proximity-induced superconducting gap in the WTe₂ for thicknesses from a monolayer up to 7 crystalline layers. At the edge of the WTe₂ monolayer, we show that the superconducting gap coexists with the characteristic spectroscopic signature of the QSH edge state [1]. Taken together, these observations provide conclusive evidence for proximity-induced superconductivity in the QSH edge state in WTe₂, a crucial step towards realizing 1D topological superconductivity and Majorana states in this van der Waals material platform.

[1] F. Lüpke, et al., arXiv:1903.00493 (2019)