Manipulating quantum channels in weak topological insulator nanoarchitectures

TL;DR

This paper explores the electronic properties of weak topological insulator nanoarchitectures, demonstrating their potential for creating disorder-immune topologically protected nanocircuits through manipulation of surface states and spectral flow analysis.

Contribution

It introduces a method to manipulate and analyze surface states in WTI nanostructures, revealing their robustness and potential for topologically protected device applications.

Findings

Surface states can be manipulated via nanosteps to create protected channels.

Spectral flow analysis shows immunity of surface modes to disorder.

WTI nanoarchitectures are promising for disorder-immune topological circuits.

Abstract

In $strong$ topological insulators protected surface states are always manifest, while in $weak$ topological insulators (WTI) the corresponding metallic surface states are either manifest or hidden, depending on the orientation of the surface. One can design a nanostep on the surface of WTI such that a protected helical channel appears along it. In a more generic WTI nanostructure, multiple sets of such quasi-1D channels emerge and are coupled to each other. We study the response of the electronic spectrum associated with such quasi-1D surface modes against a magnetic flux piercing the system in the presence of disorder, and find a non-trivial, connected spectral flow as a clear signature indicating the immunity of the surface modes to disorder. We propose that the WTI nanoarchitecture is a promising platform for realizing topologically protected nanocircuits immune to disorder.