In-surface confinement of topological insulator nanowire surface states

TL;DR

This paper demonstrates that topological insulator nanowire surface states are confined to specific surfaces due to differences in Fermi velocity, challenging the assumption of surface equivalence and impacting experimental design.

Contribution

It reveals that topological insulator surface states are surface-specific, influenced by Fermi velocity variations, which was previously unrecognized.

Findings

Surface states prefer specific nanowire surfaces.

Fermi velocity varies significantly across surfaces.

Experimental probing must consider surface-specific effects.

Abstract

The bandstructures of [110] and [001] Bi2Te3 nanowires are solved with the atomistic 20 band tight binding functionality of NEMO5. The theoretical results reveal: The popular assumption that all topological insulator wire surfaces are equivalent is inappropriate. The Fermi velocity of chemically distinct wire surfaces differs significantly which creates an effective in-surface confinement potential. As a result, topological insulator surface states prefer specific surfaces. Therefore, experiments have to be designed carefully not to probe surfaces unfavorable to the surface states (low density of states) and thereby be insensitive to the TI-effects.