Spin polarized current in a junction of zigzag carbon nanotube

TL;DR

This paper demonstrates that weak coupling in a junction of a zigzag carbon nanotube and a nonmagnetic metal can produce spin-polarized currents, controllable via gate voltage, due to magnetic edge states.

Contribution

It reveals the mechanism of spin polarization in zigzag carbon nanotube junctions and explores control via gate voltage and Coulomb interactions.

Findings

Spin-polarized current occurs under weak junction coupling.

Magnetic edge states are responsible for spin polarization.

Gate voltage can control the spin polarization.

Abstract

We investigated spin-resolved electronic transport through a junction composed of a nonmagnetic metal electrode and a zigzag carbon nanotube by means of self-consistent Green's function method in the tight binding approximation and the unrestricted Hartree-Fock approximation. Our results show that the electric current can be spin-polarized if the coupling of the junction is weak. Further calculations on spin-spin correlation and local density of states reveal the existence of magnetic edge states in zigzag carbon nanotubes, which is responsible for the observed spin-polarized current and can be controlled by applying a gate voltage. We also studied the influence of the nearest-neighbor Coulomb interaction and the junction coupling strength on the spin-polarization of the current.