Theory of superconductivity of carbon nanotubes and graphene

TL;DR

This paper proposes a new edge-state-based mechanism for superconductivity in carbon nanotubes and graphene, predicting localized superconducting regions at edges that influence Josephson current behavior.

Contribution

It introduces a novel superconductivity mechanism originating from edge states in graphene and nanotubes, distinct from bulk superconductivity, with potential experimental signatures.

Findings

Superconductivity arises from edge states specific to graphene.

Superconducting regions are localized at nanotube ends.

Josephson current depends on nanotube length and Fermi energy position.

Abstract

We present a new mechanism of carbon nanotube superconductivity that originates from edge states which are specific to graphene. Using on-site and boundary deformation potentials which do not cause bulk superconductivity, we obtain an appreciable transition temperature for the edge state. As a consequence, a metallic zigzag carbon nanotube having open boundaries can be regarded as a natural superconductor/normal metal/superconductor junction system, in which superconducting states are developed locally at both ends of the nanotube and a normal metal exists in the middle. In this case, a signal of the edge state superconductivity appears as the Josephson current which is sensitive to the length of a nanotube and the position of the Fermi energy. Such a dependence distinguishs edge state superconductivity from bulk superconductivity.