Spin-Polarized Electrons in Bilayer Graphene Flakes

TL;DR

This paper demonstrates that bilayer graphene flakes on ferromagnetic insulators can act as spin filters by exploiting exchange splitting and Fano antiresonances to produce spin-polarized currents.

Contribution

It introduces a novel approach to generate spin-polarized currents using graphene flakes influenced by ferromagnetic materials and quantum interference effects.

Findings

Spin filtering achieved via Fano antiresonances.

Net spin current can be controlled by flake length and energy.

Proposes graphene-based spin filter devices.

Abstract

We show that a bilayer graphene flake deposited above a ferromagnetic insulator can behave as a spin-filtering device. The ferromagnetic material induces exchange splitting in the graphene flake, and due to the Fano antiresonances occurring in the transmission of the graphene flake as a function of flake length and energy, it is possible to obtain a net spin current. This happens when an antiresonance for one spin channel coincides with a maximum transmission for the opposite spin. We propose these structures as a means to obtain spin-polarized currents and spin filters in graphene-based systems.