Current instability and diamagnetism in small-diameter carbon nanotubes

TL;DR

This paper studies electronic instabilities in small-diameter carbon nanotubes, revealing phase separation, pseudogap formation, and diamagnetic responses, thus advancing understanding of their low-energy electronic behavior.

Contribution

It demonstrates the breakdown of Luttinger liquid behavior in undoped (3,3) nanotubes due to phase separation and links these phenomena to experimental observations.

Findings

Phase separation into regions with opposite electronic current

Formation of a pseudogap in the single-particle spectrum

Divergent diamagnetic susceptibility observed

Abstract

We investigate the electronic instabilities in carbon nanotubes of short radius, looking for the breakdown of the Luttinger liquid regime from the singular behavior of the charge stiffnesses at low energies. We show that such a breakdown is realized in the undoped (3,3) nanotubes through the onset of phase separation into regions with opposite electronic current. The phenomenology derived from this regime is consistent with the formation of a pseudogap in the single-particle spectrum as well as with a divergent diamagnetic susceptibility, as observed in the experiments carried out in carbon nanotubes of small diameter.