Doped carbon nanotubes as a model system of biased graphene

TL;DR

This study investigates the density of states in potassium-intercalated carbon nanotubes, revealing Fermi-liquid behavior and proposing their use as a model for biased graphene due to their comprehensive Brillouin zone coverage.

Contribution

It provides experimental and theoretical analysis of DOS in doped nanotubes, demonstrating their suitability as a model system for biased graphene.

Findings

Presence of electron states indicating Fermi-liquid behavior

Minimal correlation effects despite Luttinger-liquid behavior in pristine nanotubes

Nanotube ensemble maps the entire Brillouin zone of graphene

Abstract

Albeit difficult to access experimentally, the density of states (DOS) is a key parameter in solid state systems which governs several important phenomena including transport, magnetism, thermal, and thermoelectric properties. We study DOS in an ensemble of potassium intercalated single-wall carbon nanotubes (SWCNT) and show using electron spin resonance spectroscopy that a sizeable number of electron states are present, which gives rise to a Fermi-liquid behavior in this material. A comparison between theoretical and the experimental DOS indicates that it does not display significant correlation effects, even though the pristine nanotube material shows a Luttinger-liquid behavior. We argue that the carbon nanotube ensemble essentially maps out the whole Brillouin zone of graphene thus it acts as a model system of biased graphene.