Wavevector-dependent spin filtering and spin transport through magnetic barriers in graphene

TL;DR

This paper investigates how magnetic barriers in graphene can be used to control spin transport, revealing wavevector-dependent spin filtering effects that are enhanced in double barrier setups, achieving near-perfect spin polarization.

Contribution

It introduces a detailed analysis of spin-resolved transport in graphene nanostructures considering both orbital magnetic effects and spin splitting, highlighting a novel wavevector-dependent spin filtering mechanism.

Findings

Single magnetic barrier causes wavevector-dependent spin filtering.

Double barrier configuration significantly enhances spin polarization.

Spin polarization can reach up to 100% with optimized barrier spacing.

Abstract

We study the spin-resolved transport through magnetic nanostructures in monolayer and bilayer graphene. We take into account both the orbital effect of the inhomogeneous perpendicular magnetic field as well as the in-plane spin splitting due to the Zeeman interaction and to the exchange coupling possibly induced by the proximity of a ferromagnetic insulator. We find that a single barrier exhibits a wavevector-dependent spin filtering effect at energies close to the transmission threshold. This effect is significantly enhanced in a resonant double barrier configuration, where the spin polarization of the outgoing current can be increased up to 100% by increasing the distance between the barriers.