Low-energy electron transport in semimetal graphene ribbon junctions

Based on the nearest-neighbor tight-binding model, we present analytical description of single-mode electron transport through a common-edged junction connecting two semimetal armchair ribbons of different width. The results obtained demonstrate the transmission suppression in the vicinity of the neutrality point except for the junction of the ribbons consisting of 3p-1 and 3p+2 dimer lines, p is odd. Unlike other interconnections, this junction is shown to be free of local levels arising at the junction interface and exhibits electron backscattering to be inversely as the square of 2p+1. We also demonstrate that non-zero propagation through a graphene junction can be described by the same relation as that for linear undimerized chain of atoms with one defect bond.