A spin-filter device based on armchair graphene nanoribbons

TL;DR

This paper proposes a graphene nanoribbon-based spin-filter device that achieves high spin polarization, controllable via gate voltage, using Landauer-Buttiker formalism and Hubbard model calculations.

Contribution

It introduces a novel spin-filter device based on armchair graphene nanoribbons with tunable efficiency without magnetic electrodes.

Findings

Achieves up to 90% spin polarization.

Operates without magnetic electrodes or external magnetic fields.

Efficiency can be controlled by gate voltage.

Abstract

The coherent spin-polarized electron transport through a zigzag-edge graphene flake (ZGF), sandwiched between two semi-infinite armchair graphene nanoribbons, is investigated by means of Landauer-Buttiker formalism. To study the edge magnetism of the ZGF, we use the half-filled Hubbard model within the Hartree-Fock approximation. The results show that the junction acts as a spin filter with high degree of spin polarization in the absence of magnetic electrodes and external fields. By applying a gate voltage the spin-filtering efficiency of this device can be effectively controlled and the spin polarization can reach values as high as 90%.