Giant Magnetoresistance in Bilayer Graphene Nanoflakes

TL;DR

This study demonstrates giant magnetoresistance and perfect spin polarization in bilayer graphene nanoflakes, tunable by geometry and magnetic field, with potential applications in spintronic devices.

Contribution

It reveals that AB-stacked bilayer graphene nanoflakes can exhibit giant magnetoresistance up to 10^6%, tunable by size and magnetic field, advancing graphene-based spintronics.

Findings

GMR up to 10^6% observed in bilayer graphene nanoflakes.

Magnetoresistance and spin polarization are tunable by geometry and magnetic field.

GMR increases with length and decreases with width of the nanoflake.

Abstract

Coherent spin transport through bilayer graphene (BLG) nanoflakes sandwiched between two electrodes made of single-layer zigzag graphene nanoribbon was investigated by means of Landauer-Buttiker formalism. Application of a magnetic field only on BLG structure as a channel produces a perfect spin polarization in a large energy region. Moreover, the conductance could be strongly modulated by magnetization of the zigzag edge of AB-stacked BLG, and the junction, entirely made of carbon, produces a giant magnetoresistance (GMR) up to $10^6\%$. Intestinally, GMR and spin polarization could be tuned by varying BLG width and length. Generally, MR in a AB-stacked BLG strongly increases (decreases) with length (width).