Electron transport through phenylene sandwiched between zigzag graphene nanoribbons.

We study systematically the electron transport through a phenylene rotor with an axis of atomic carbon chain (CPC) connected to twofold symmetric electrodes of nonmagnetic zigzag graphene nanoribbons. The density functional theory combined with the nonequilibrium Green's function method is employed for the simulation. The CPC rotor is conductive with parabolic I-V characteristic when its ring is coplanar with the electrodes. Its rotation modulates the symmetry of its electron states and their matching to the states in the electrodes. The I-V curve then becomes characterized by sharp peaks with strong negative differential resistance (NDR) in a large range of the rotation angle. The corresponding shift of transport modes in energy with the rotation opens a way to efficient and accurate manipulation of NDR. [ABSTRACT FROM AUTHOR]