Electron Interactions and Scaling Relations for Optical Excitations in Carbon Nanotubes

TL;DR

This paper explains deviations in optical transition energies of carbon nanotubes from noninteracting models by incorporating electron interactions, revealing that large-radius nanotubes exhibit effects similar to graphene due to Coulomb interactions.

Contribution

The paper develops a theory for large-radius carbon nanotubes based on graphene physics, accounting for electron interactions and explaining experimental optical data.

Findings

Interactions cause logarithmic corrections to self energy.

Excitonic effects nearly cancel self energy corrections.

Optical transitions are dominated by graphene-like self energy effects.

Abstract

Recent fluorescence spectroscopy experiments on single wall carbon nanotubes reveal substantial deviations of observed absorption and emission energies from predictions of noninteracting models of the electronic structure. Nonetheless, the data for nearly armchair nanotubes obey a nonlinear scaling relation as a function the tube radius $R$. We show that these effects can be understood in a theory of large radius tubes, derived from the theory of two dimensional graphene where the coulomb interaction leads to a logarithmic correction to the electronic self energy and marginal Fermi liquid behavior. Interactions on length scales larger than the tube circumference lead to strong self energy and excitonic effects that compete and nearly cancel so that the observed optical transitions are dominated by the graphene self energy effects.