LAUSR

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 ∼ 10 cm of Coulomb impurities. It is believed that a MBS device can function only if a subband energy fluctuation due to the long-range Coulomb potential Γ is smaller than the subband gap ∆. Here we calculate Γ for recently experimentally studied large-dielectric-constant (Bi1−xSbx)2Te3 TI wires in a small-dielectric-constant environment (no superconductor). We show that provided by such a dielectric constant contrast confinement of electric field of impurities within the wire allows more distant impurities to contribute into Γ, leading to Γ ∼ 3∆. We also calculate a TI wire resistance as a function of the carrier concentration due to scattering on Coulomb and neutral impurities, and do not find observable discrete subband spectrum related oscillations at N & 10 cm.