Electronic properties of the partially hydrogenated armchair carbon nanotubes

TL;DR

This study uses density functional theory to explore how hydrogenation affects the electronic properties of armchair carbon nanotubes, revealing a transition from metallic to semiconducting behavior with magnetic ordering.

Contribution

It provides new insights into hydrogen-induced electronic and magnetic modifications in armchair nanotubes, highlighting the formation of H chains and their effects.

Findings

Hydrogen prefers forming monoatomic chains along the nanotube axis.

Hydrogenation induces a band gap of approximately 0.6 eV.

Magnetic moments exhibit antiferromagnetic coupling near H chains.

Abstract

By means of pseudopotential calculations based on density functional theory (DFT) we studied the effect of hydrogenation on electronic properties of armchair single-wall carbon nanotubes. The calculations demonstrate strong preference for formation of monoatomic H chains along the (5,5) nanotube axis with the H binding in an infinite H chain reaching the value of 2.58 eV per atom. Upon formation of chains of H adatoms, initially metallic (5,5) nanotubes change electronic structure to the semiconducting. The opening of the band gap of $\sim$0.6 eV is accompanied with antiferromagnetic coupling of ferromagnetically ordered magnetic moments on C atoms in vicinity of the H chain. These electronic properties are strikingly similar to those previously observed in narrow graphene nanoribbons with zigzag edges.