Robust and fragile Majorana bound states in proximitized topological insulator nanoribbons

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.

12 pages, 5 figures

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Cited by in corpus (7)

• Robust and fragile Majorana bound states in proximitized topological insulator nanoribbons
• Long-range crossed Andreev reflection in topological insulator nanowires proximitized by a superconductor
• Low-energy modeling of three-dimensional topological insulator nanostructures
• Characterizing the chemical potential disorder in the topological insulator (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$ thin films
• Robust Majorana bound states in magnetic topological insulator nanoribbons with fragile chiral edge channels
• Optimizing proximitized magnetic topological insulator nanoribbons for Majorana bound states
• In-plane magnetic field driven conductance modulations in topological insulator kinks