Electron transport in graphene nanoribbons under a central potential modulation

We study electron transport in graphene nanoribbons (GNs) under a one-dimensional central potential. Two kinds of structures are considered: armchair-edged GN (AGN) where a central potential is applied on the central dimer chain, and zigzag-edged GN (ZGN) where a potential is applied on the central zigzag chain. Both nanoribbons show unique electronic structure and interesting transport properties under potential modulation. Without considering edge effect, a metallic AGN is still metallic after potential modulation. However, if the edge effect is considered, an AGN under potential modulation can be either semiconducting or metallic depending on the potential strength. The AGN transits from semiconducting to metallic and then to semiconducting again with the potential increase. As to ZGN, the potential on the central zigzag chain also greatly affect the quantum conductance. A ZGN will transit from metallic to semiconducting as the potential strength exceeds critical value. All transitions of AGN and ZGN are correlated with the localized state on the central potential chain which induces a quantum channel along the chain.