We report the coherent spin-polarized transport through a pure and doped zigzag-edge graphene flake (ZGF) connected from left and right to two armchair graphene nanoribbons, using the Hubbard model in the nearest neighbor approximation within the framework of the Green function\'s technique and Landauer formalism. We consider the effect of boron impurity atoms in three different spatial configurations in the central part of the system (ZGF). We found that the pure system shows considerable spin filtering properties, which is due to the interaction of the spin of the carriers with the local zigzag-edge magnetism. However, our results show that the presence of the impurity atoms reduces the spin filtering property which could be due to the decrease in the effective spin interaction.

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