Quantum conductance of graphene nanoribbons with edge defects

The conductance of metallic graphene nanoribbons (GNRs) with single defects and weak disorder at their edges is investigated in a tight-binding model. We find that a single edge defect will induce quasilocalized states and consequently cause zero-conductance dips. The center energies and breadths of such dips are strongly dependent on the geometry of GNRs. Armchair GNRs are more sensitive to a vacancy than zigzag GNRs, but are less sensitive to a weak scatter. More importantly, we find that with a weak disorder, zigzag GNRs will change from metallic to semiconducting due to Anderson localization. However, a weak disorder only slightly affects the conductance of armchair GNRs.