Half-metallic zigzag carbon nanotube dots

TL;DR

This study uses first-principles calculations to explore the electronic and magnetic properties of finite zigzag carbon nanotubes, revealing their intrinsic spin-polarized ground states and potential for electric field-induced half-metallicity.

Contribution

It demonstrates that all studied zigzag carbon nanotubes have a spin-polarized ground state with edge localization, and shows how their electronic properties can be tuned by length and external electric fields.

Findings

All studied nanotubes exhibit a spin-polarized ground state.

Shorter segments may maintain spin-ordering at room temperature.

Half-metallicity can be induced by an external axial electric field.

Abstract

A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of finite zigzag carbon nanotubes is presented. Unlike previous reports, we find that all nanotubes studied present a spin-polarized ground state, where opposite spins are localized at the two zigzag edges in a long-range antifferomagnetic configuration. Relative stability analysis of the different spin states indicate that, for the shorter segments, spin-ordering should be present even at room temperature. The energy gap between the highest occupied and the lowest unoccupied molecular orbitals of the finite systems is found to be inversely proportional to the nanotubes segments length, suggesting a route to control their electronic properties. Similar to the case of zigzag graphene nanoribbons, half-metallic behavior is obtained under the influence of an external axial electric field.