Impurity effects in twisted carbon nanotubes

TL;DR

This paper investigates how impurity atoms affect the electronic spectra of twisted carbon nanotubes, especially when 1D Weyl modes are present, revealing impurity-induced mobility gaps and delocalized states with potential applications.

Contribution

It introduces a detailed analysis of impurity effects on twisted nanotubes' electronic properties, focusing on Weyl modes and comparing with other carbon-based materials.

Findings

Impurity concentration induces a mobility gap near impurity levels.

Higher impurity levels lead to narrow delocalized states within the mobility gap.

Hybridization of Weyl modes with impurity states significantly alters electronic spectra.

Abstract

We consider electronic spectra of twisted carbon nanotubes and their perturbation by impurity atoms absorbed at different positions on nanotube surface within the framework of Anderson hybrid model. A special attention is given to the cases when 1D Weyl (massless Dirac) modes are present in the nanotube spectrum and their hybridization with localized impurity states produces, with growing impurity concentration c, onset of a mobility gap near the impurity level and then opening, at yet higher c, of some narrow range of delocalized states within this mobility gap. Such behaviors are compared with similar effects in the previously studied 2D graphene, carbon nanoribbons, and non-twisted carbon nanotubes. Some possible practical applications are discussed.