Graphene valley pseudospin filter using an extended line defect*

Although graphene exhibits excellent electron and thermal transport properties, it does not have an intrinsic band gap, required to use graphene as a replacement material for silicon and other semiconductors in conventional electronics. The band structure of graphene with its two cones near the Fermi level, however, offers opportunities to develop non-traditional applications. One such avenue is to exploit the valley degeneracy in graphene to develop valleytronics. A central component in valleytronics is the valley filter, just as the spin filter is central in spintronics. Herein, we present a two-dimensional valley filter based on scattering of electrons and holes off a recently observed extended line defect [Nat. Nanotech. \textbf{5}, 326 (2010)] within graphene. The transmission probability depends strongly on the valley pseudospin and the angle of incidence of the incident quasiparticles. Quasiparticles arriving at the line defect at a high angle of incidence lead to a valley polarization of the transmitted beam that is near 100 percent.