Single-Parameter Quantum Pumping in Graphene Nanoribbons with Staggered Sublattice Potential

We present a theoretical study of quantum charge pumping in metallic armchair graphene nanoribbons using the Floquet–Green function method. A central part of the ribbon acting as the scattering region is supposed to have staggered sublattice potential to open a finite band gap. A single ac gate is asymmetrically applied to a part of the scattering region to drive the pumping. Corresponding to the gap edges, there are two pumped current peaks with opposite current directions, which can be reversed by changing the position of the ac gate relative to the scattering region. The effects of the parameters, such as the staggered sublattice potential, the driving frequency and the geometric parameters of the structure, on the pumping are discussed.