Spin-dependent transport properties of AA-stacked bilayer graphene nanoribbon

In this paper, the spin-dependent transport of a spin-valve, based on bilayer graphene in which the AA-stacked bilayer zigzag graphene nanoribbon (BLG) connected to two ferromagnetic (FM) semi-infinite single-layer zigzag graphene nanoribbons (FM/BLG/FM system), is numerically studied. Using the non-equilibrium Green's function method and tight-binding model in the framework of Landauer-Büttiker formalism, the spin-dependent transmission function, current and tunnel magnetoresistance of the system are calculated. Results show that the transmission function is always nonzero near the zero energy for the parallel alignment of electrode magnetizations, while it is zero for the antiparallel alignment due to the band-selective rule. Consequently, there is a region for the tunnel magnetoresistance with the value of 100%. The magnitude of this region depends on the strength of magnetization in ferromagnetic electrodes. Also, the effects of bilayer/single-layer coupling geometry,inter-layer coupling strength and width of BLG on the spin-dependent transport of the system are investigated. These results can be useful for designing graphene based spintronic devices.