Octagonal defects at carbon nanotube junctions.

W Jaskólski,A Ayuela,M Pelc,Leonor Chico

doi:10.1155/2013/658292

Abstract

We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (E F). The reconstructed junction has only one state near E F, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system.

Highlights

Carbon nanotubes can behave as metals or semiconductors depending on their geometry and diameter
A large number of works have been devoted to the study of electronic and transport properties of single interfaces [5,6,7], double junctions [8], quantum dots [9], and carbon nanotube superlattices [10, 11]
As discussed in the previous section, when joining the (14,0) tube to a diagonally cut (8,0) tube, an 8R octagonal defect appears at the back of the knee

Summary

Introduction

Carbon nanotubes can behave as metals or semiconductors depending on their geometry and diameter. The possibility of joining different tubes has been an early theoretical proposal [1,2,3], later experimentally verified [4] To achieve such junctions, topological defects have to be introduced in the hexagonal carbon lattice. A large number of works have been devoted to the study of electronic and transport properties of single interfaces [5,6,7], double junctions [8], quantum dots [9], and carbon nanotube superlattices [10, 11] Junctions in such systems are usually realized by introducing pentagon/heptagon (5/7) topological defects at interfaces between the nanotubes, other proposals involving different kinds of defects, such as octagons, have been made [12]. We show that these octagonal defects lead to state localization at the Fermi energy

System and Geometry

Model and Computational Details

Results

Summary and Conclusions