Vertical-strain-induced spin-splitting in zigzag graphene nanoribbons

We report a first-principles study of the spintronic properties of zigzag graphene nanoribbons under vertical strain. An apparent spin-splitting of the energy band is obtained when a local deformation is created by the vertically applied strain. In particular, it is found that the spin-splitting is most obvious at the bottom of the conduction band. The value of the spin-splitting is related to the position, depth and size of the deformation. By changing the position of the local deformation from the edge to the center of the ribbon, the optimal position is obtained. Detailed calculations at the optimal position show that, for a given size, the spin-splitting value increases with the depth of the deformation, while for a given depth, the spin-splitting value decreases with the size of the deformation.