Interface States in Carbon Nanotube Junctions: Rolling up graphene

TL;DR

This paper explains the origin and properties of interface states in carbon nanotube junctions, linking them to zigzag edge states in graphene, and offers insights into their spatial localization and decay lengths.

Contribution

It provides a new explanation for interface states in nanotube junctions, relating them to graphene zigzag edge states rather than topological defects.

Findings

Interface states are related to zigzag edge states in graphene.

Spatial localization of interface states varies and can extend into both sides.

The decay length of interface states can be explained without topological defects.

Abstract

We study the origin of interface states in carbon nanotube intramolecular junctions between achiral tubes. By applying the Born-von Karman boundary condition to an interface between armchair- and zigzag-terminated graphene layers, we are able to explain their number and energies. We show that these interface states, costumarily attributed to the presence of topological defects, are actually related to zigzag edge states, as those of graphene zigzag nanoribbons. Spatial localization of interface states is seen to vary greatly, and may extend appreciably into either side of the junction. Our results give an alternative explanation to the unusual decay length measured for interface states of semiconductor nanotube junctions, and could be further tested by local probe spectroscopies.