Schematic presentation of the modified construction of the graphene spin filter with monolayers of graphene and Au additionally inserted between the graphene sheet and the Ni electrodes (a). Under application of a perpendicular magnetic field the orientation of the spin precesses with moving electrons toward the second Ni electrode (b). When the spin moment of the electrons in the graphene aligns with that in the second Ni electrode the electrons can be injected into the Ni, and a spin current flows through the system.