Robust spin polarization and giant magnetoresistance based on ferromagnetic bearded zigzag graphene nanoribbons

Ferromagnetic bearded zigzag graphene nanoribbons (GNRs) are proposed as promising candidates for achieving robust spin polarization and giant magnetoresistance (GMR). Numerical calculations using non-equilibrium Green’s function, based on a GNR device with width in the order of 10 nm, reveal significant spin-dependent transport properties under varying magnetizations and Fermi energy. In the parallel magnetization configuration, the conductance exhibits quantized plateaus of $e^2/h$, corresponding to perfect spin polarization. In the antiparallel configuration, the conductance vanishes, ensuring a high GMR ratio. The spin-dependent band structure analysis demonstrates the half-metallic nature of the bearded GNRs, which act as conductors for one spin orientation while insulating the opposite. The spin-polarized current remains robust even in the presence of Anderson disorder, ensuring stability against localized scattering effects. The proposed GNR device operates as an efficient spin filter and valve. These findings highlight the potential of ferromagnetic GNRs for advanced spintronic applications, enabling electrically controlled spin-polarized transport and giant magnetoresistance in nanoscale devices.