Pure valley current generation in graphene with a Dirac gap by quantum pumping

We studied the pure valley current generated by adiabatic quantum pumping in a monolayer graphene with a gap generated by a substrate. The generation of the quantum-pumped pure valley current requires the presence of the antiparallel magnetic fields of two magnetic strips and the electrical potential barriers of three metal gates. The Fabry-Perot resonances in the structure play an import role in the formation of the pumped current. By changing the amplitude of the ac voltage and the Fermi level, the pumped current can be modified. The proposed technique can have applications in the development of graphene valleytronic devices. (C) 2014 The Japan Society of Applied Physics