Spin polarization and magnetoresistance through a ferromagnetic barrier in bilayer graphene

TL;DR

This paper investigates spin-dependent transport and magnetoresistance in a ferromagnetic bilayer graphene nanojunction, revealing high spin polarization and tunable magnetoresistance based on magnetic configurations.

Contribution

It introduces a detailed analysis of spin transport in ferromagnetic bilayer graphene with gate control, highlighting the potential for high magnetoresistance in such structures.

Findings

Maximum spin polarization near resonant states in parallel configuration

Semiconducting behavior and no spin filtering in antiparallel configuration

Large magnetoresistance achievable by changing magnetic configurations

Abstract

We study spin dependent transport through a magnetic bilayer graphene nanojunction configured as two dimensional normal/ferromagnetic/normal structure where the gate-voltage is applied on the layers of ferromagnetic graphene. Based on the fourband Hamiltonian, conductance is calculated by using Landauer Butikker formula at zero temperature. For parallel configuration of the ferromagnetic layers of bilayer graphene, the energy band structure is metallic and spin polarization reaches to its maximum value close to the resonant states, while for antiparallel configuration, the nanojunction behaves as a semiconductor and there is no spin filtering. As a result, a huge magnetoresistance is achievable by altering the configurations of ferromagnetic graphene especially around the band gap.