Metal-Semiconductor Transition in Armchair Carbon Nanotubes by Symmetry Breaking

TL;DR

This paper investigates how angular-dependent potentials can induce a metal-semiconductor transition in armchair carbon nanotubes by breaking their symmetry, leading to bandgap openings.

Contribution

It introduces a symmetry-based framework to predict bandgap openings in armchair nanotubes under angular potentials, expanding understanding of their electronic modifications.

Findings

Bandgap opening occurs when specific symmetry conditions are met.

The bandgap size depends on potential strength and nanotube radius.

Proposes a mechanism for metal-semiconductor transition via combined perturbations.

Abstract

The electronic band structure of armchair carbon nanotubes may be considerably modified by potentials with angular dependence. Different angular modes V_q ~ cos(q*theta) have been studied within a tight-binding scheme. Using symmetry arguments, we demonstrate a bandgap opening in these metallic nanotubes when certain selection rules are satisfied for both potential and nanotube structure. We estimate the bandgap opening as a function of both the external potential strength and the nanotube radius and suggest an effective mechanism of metal-semiconductor transition by combination of different forms of perturbations.