1D topological superconductivity and Majorana states in van der Waals heterostructures characterized by scanning probe microscopy

• Applicant: Dr. Felix Lüpke
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443416235

Topological superconductivity is an exotic state of matter with potential applications in quantum computing. A promising approach to realize topological superconductivity is to use a conventional superconductor to induce superconductivity in a topological edge state via the superconducting proximity effect. Using a newly developed sample fabrication technique, the ‘dry-transfer flip technique’, as well as epitaxial thin films which are grown by our collaborators, we propose to create van der Waals (vdW) heterostructures of two-dimensional, atomically thin layers of topological insulators WTe2 and (Bi(1-x)Sb(x))2Te3 on superconducting NbSe2 and FeTe(1-y)Se(y). Using scanning probe microscopy at low temperatures and in ultra-high vacuum, we then characterize the induced superconductivity in the topological edge state. By combination of a topological superconductor with some form of magnetism, e.g. a magnetic layer, a magnetic cluster or by application of an external magnetic field, so-called Majorana quasi-particles can be created in the topological superconductor. We propose to realize and study Majorana states created in the vdW heterostructures to gain a deeper understanding of the underlying physics. Another sample system in which we propose to realize Majorana states are atomically thin layers of NbSe2 which are placed on a vdW magnet such as Fe3Ge1Te2. Our experimental characterization will be supported by theoretical calculations from our collaborators within the programme.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2244: 2D Materials – Physics of van der Waals [hetero]structures (2DMP)
• Co-Investigator: Professor Dr. Stefan F. Tautz