Strong localization in defective carbon nanotubes: a recursive Green's function study

TL;DR

This study investigates how defects affect electron transport in carbon nanotubes, revealing strong localization effects and providing detailed analysis of conductance behavior under various conditions using a recursive Green's function approach.

Contribution

It introduces a fast, scalable Green's function method to analyze defect-induced localization in large carbon nanotubes with detailed statistical and parametric insights.

Findings

Conductance scales exponentially with defect number in large disorder regimes.

System exhibits strong Anderson localization with a measurable localization length.

Conductance and localization length depend systematically on defect density, CNT diameter, and temperature.

Abstract

We study the transport properties of defective single-walled armchair carbon nanotubes (CNTs) on a mesoscopic length scale. Monovacancies and divancancies are positioned randomly along the CNT. The calculations are based on a fast, linearly scaling recursive Green's function formalism that allows us to treat large systems quantum-mechanically. The electronic structure of the CNT is described by a density-functional-based tight-binding model. We determine the influence of the defects on the transmission function for a given defect density by statistical analysis. We show that the system is in the regime of strong localization (i.e. Anderson localization). In the limit of large disorder the conductance scales exponentially with the number of defects. This allows us to extract the localization length. Furthermore, we study in a systematic and comprehensive way, how the conductance, the conductance distribution, and the localization length depend on defect probability, CNT diameter, and temperature.