Robust and fragile Majorana bound states in proximitized topological insulator nanoribbons

Dennis Heffels; Declan Burke; Malcolm R. Connolly; Peter Schüffelgen; Detlev Grützmacher; Kristof Moors

doi:10.3390/nano13040723

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arXiv · 2212.14482

Robust and fragile Majorana bound states in proximitized topological insulator nanoribbons

Dennis Heffels·Declan Burke·Malcolm R. Connolly·Peter Schüffelgen·Detlev Grützmacher·Kristof Moors

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Abstract

Topological insulator (TI) nanoribbons with proximity-induced superconductivity are a promising platform for Majorana bound states (MBSs). In this work, we consider a detailed modeling approach for a TI nanoribbon in contact with a superconductor via its top surface, which induces a superconducting gap in its surface-state spectrum. The system displays a rich phase diagram with different numbers of end-localized MBSs as a function of chemical potential and magnetic flux piercing the cross section of the ribbon. These MBSs can be robust or fragile upon consideration of electrostatic disorder. We simulate a tunneling spectroscopy setup to probe the different topological phases of top-proximitized TI nanoribbons. Our simulation results indicate that a top-proximitized TI nanoribbon is ideally suited for realizing fully gapped topological superconductivity, in particular when the Fermi level is pinned near the Dirac point. In this regime, the setup yields a single pair of MBSs, well separated at opposite ends of the proximitized ribbon, which gives rise to a robust quantized zero-bias conductance peak.

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Dennis Heffels, Declan Burke, Malcolm R. Connolly, Peter Schüffelgen, Detlev Grützmacher, Kristof Moors. 2022-12-29. Robust and fragile Majorana bound states in proximitized topological insulator nanoribbons. https://doi.org/10.3390/nano13040723

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