Quantum pumping with adiabatically modulated barriers in graphene

We study the adiabatic quantum pumping characteristics in graphene modulated by two oscillating gate potentials out of phase. The angular and energy dependence of the pumped current (PC) is presented. The direction of the PC can be reversed when a high potential barrier demonstrates stronger transparency than a low one, which results from the Klein paradox. The underlying physics of the pumping process is illuminated. (C) 2009 American Institute of Physics. [doi:10.1063/1.3236785]