Disorder, pseudospins, and backscattering in carbon nanotubes

TL;DR

This paper investigates how disorder affects electrical conduction in carbon nanotubes, revealing that long-range disorder and pseudospin properties suppress backscattering in metallic tubes, explaining experimental differences between metallic and semiconducting types.

Contribution

It provides a theoretical explanation for the differing mean free paths in metallic and semiconducting nanotubes based on disorder range and pseudospin effects, supported by tight-binding calculations.

Findings

Long-range disorder leads to reduced backscattering in metallic nanotubes.

Pseudospin suppresses scattering in metallic but not in semiconducting tubes.

Theoretical results align with experimental observations of mean free paths.

Abstract

We address the effects of disorder on the conducting properties of metal and semiconducting carbon nanotubes. Experimentally, the mean free path is found to be much larger in metallic tubes than in doped semiconducting tubes. We show that this result can be understood theoretically if the disorder potential is long-ranged. The effects of a pseudospin index that describes the internal sublattice structure of the states lead to a suppression of scattering in metallic tubes, but not in semiconducting tubes. This conclusion is supported by tight-binding calculations.