Disorder effects in topological insulator nanowires

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Abstract

Three-dimensional topological insulator (TI) nanowires with quantized surface subband spectra are studied as a main component of Majorana bound states (MBS) devices. However, such wires are known to have large concentration N∼1019cm-3 of Coulomb impurities. It is believed that a MBS device can function only if the amplitude of long-range fluctuations of the random Coulomb potential Γ is smaller than the subband gap Δ. Here we calculate Γ for recently experimentally studied large-dielectric-constant (Bi1-xSbx)2Te3 wires in a small-dielectric-constant environment (no superconductor). We show that provided by such a dielectric-constant contrast, the confinement of electric field of impurities within the wire allows more distant impurities to contribute into Γ, leading to Γ∼3Δ. We also calculate a TI wire resistance as a function of the Fermi level and carrier concentration due to scattering on Coulomb and neutral impurities and do not find observable discrete subband-spectrum-related oscillations at N≳1018cm-3.

Original languageEnglish (US)
Article number054205
JournalPhysical Review B
Volume104
Issue number5
DOIs
StatePublished - Aug 1 2021

Bibliographical note

Funding Information:
We are grateful to Y. Ando, A. Kamenev, H. Legg, V. Pribiag, A. Rosch, and B. Skinner for reading the paper and useful comments. Y.H. was partially supported by the William I. Fine Theoretical Physics Institute.

Publisher Copyright:
© 2021 American Physical Society.

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