Resonant single-parameter pumping in graphene

Abstract: We present results for non-adiabatic single-parameter pumping in a ballistic graphene field-effect transistor. We investigate how scattering from an ac-driven top gate results in dc charge current from source to drain in an asymmetric setup caused either by geometry of the device or different doping of leads. Charge current is computed using Floquet scattering matrix approach in Landauer-B\"uttiker operator formalism. We single out two mechanisms contributing to the pumped current: Fabry-P\'erot interference in open channels and quasibound state resonant scattering through closed channels. We identify two distinct parameter regimes based on the quasibound state scattering mechanism: high and low doping of contacts compared to the frequency of the ac drive. We show that the latter regime results in a stronger peak pump current. We discuss how back gate potential and temperature dependence can be used to change the direction of the pumped current, operating the device as a switch.