Twist instability in strongly correlated carbon nanotubes

TL;DR

This paper demonstrates that strong electron correlations in armchair carbon nanotubes can induce a twist Peierls instability, leading to a spontaneous lattice twist and a gapped ground state, with outcomes depending on tube width and scattering processes.

Contribution

It reveals how strong correlations enhance the twist instability in carbon nanotubes and explores the competition between electron-electron and electron-phonon interactions.

Findings

Twist instability can occur in free-standing (5,5) nanotubes.

Umklapp scattering influences the stability of the twist phase.

Narrow tubes favor the twist instability over competing processes.

Abstract

We show that strong Luttinger correlations of the electron liquid in armchair carbon nanotubes lead to a significant enhancement of the onset temperature of the putative twist Peierls instability. The instability results in a spontaneous uniform twist deformation of the lattice at low temperatures, and a gapped ground state. Depending on values of the coupling constants the umklapp electron scattering processes can assist or compete with the twist instability. In case of the competition the umklapp processes win in wide tubes. In narrow tubes the outcome of the competition depends on the relative strength of the e-e and e-ph backscattering. Our estimates show that the twist instability may be realized in free standing (5,5) tubes.