Correlation Effects in Carbon Nanotubes

TL;DR

This paper investigates how Coulomb interactions influence the electronic properties of single-wall carbon nanotubes, revealing potential for superconductivity driven by electronic correlations.

Contribution

It maps the low-energy behavior of armchair nanotubes to a 2-chain Hubbard model, showing how interactions induce gaps and suggest possible superconductivity.

Findings

Charge and spin gaps are exponentially small for large N.

Resistivity due to scattering is linear in temperature.

Doped nanotubes may exhibit electronic superconductivity.

Abstract

We consider the effects of Coulomb interactions on single-wall carbon nanotubes using an on-site Hubbard interaction, u. For the (N,N) armchair tubes the low energy theory is shown to be identical to a 2-chain Hubbard model at half-filling, with an effective interaction u_N = u/N. Umklapp scattering leads to gaps in the spectrum of charge and spin excitations which are exponentially small for large N. Above the gaps the intrinsic nanotube resistivity due to these scattering processes is linear in temperature, as observed experimentally. The presence of "d-wave" superconductivity in the 2-chain Hubbard model away from half-filling suggests that doped armchair nanotubes might exhibit superconductity with a purely electronic mechanism.