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TT: Fachverband Tiefe Temperaturen

TT 57: Topology: Poster

TT 57.24: Poster

Mittwoch, 20. März 2024, 15:00–18:00, Poster E

Stability of Majorana Fermions in Coulomb-Disordered Topological Insulator Nanowires — •Leonard Kaufhold — Institute for theoretical physics, University of Cologne, Germany

A topological insulator (TI) nanowire, proximity-coupled to an s-wave superconductor (SC) and subject to a longitudinal magnetic field can, in principle, be brought into an effectively spinless superconducting phase under a relatively large region of realistically accessible parameter space and therefore host Majorana Bound States (MBS) at its ends. Due to their non-Abelian statistics, devices that can manifest MBS are a promising candidate for fault-tolerant quantum computing. A TI however, is typically realized as a heavily doped semiconductor with a donor density in the order of *10¹⁹cm-3. The random potential arising from these impurities by themselves is much larger than the electronic band gap of the surface states due to dielectric confinement, easily destroying their one-dimensional nature necessary exhibit a topologically superconducting phase along the entire wire. Although this potential is screened by the metallic surface states as well as the superconductor, the ultimate fate of the MBS, i.e. whether they can "survive" the screened potential, is not at all obvious. On this poster, we will provide a general review of the TI-SC hybrid nanowire and numerically investigate its phase space based on Andreev spectra, edge state localization and topological invariants.

Keywords: Nanowires; Superconductivity; Majorana Fermions; Disorder