Quantum pumping in graphene nanoribbons at resonant transmission
National Research Nuclear University “MEPhI” - 115409, Kashirskoe sh., 31, Moscow, Russia
2 Russian Research Centre “Kurchatov Institute” - 123182, pl. Kurchatova, 1, Moscow, Russia
Accepted: 9 November 2010
Adiabatic quantum charge pumping in graphene nanoribbon double-barrier structures with armchair and zigzag edges in the resonant transmission regime is analyzed. Using the recursive Green's function method we numerically calculate the pumped charge for pumping contours encircling a resonance. We find that for armchair ribbons the whole resonance line contributes to the pumping of a single electron (ignoring double-spin degeneracy) per cycle through the device. The case of zigzag ribbons is more interesting due to zero-conductance resonances. These resonances separate the whole resonance line into several parts, each of which corresponds to the pumping of a single electron through the device. Moreover, in contrast to armchair ribbons, one electron can be pumped from the left lead to the right one or backwards. The current direction depends on the particular part of the resonance line encircled by the pumping contour.
PACS: 72.80.Vp – Electronic transport in graphene / 73.23.-b – Electronic transport in mesoscopic systems / 73.23.Ad – Ballistic transport
© EPLA, 2010