Controlled Growth of a Line Defect in Graphene and Implications for   Gate-Tunable Valley Filtering
  Atomically precise tailoring of graphene can enable unusual transport pathways and new nanometer-scale functional devices. Here we describe a recipe for the controlled production of highly regular "5-5-8" line defects in graphene by means of simultaneous electron irradiation and Joule heating by applied electric current. High-resolution transmission electron microscopy reveals individual steps of the growth process. Extending earlier theoretical work suggesting valley-discriminating capabilities of a graphene 5-5-8 line defect, we perform first-principles calculations of transport and find a strong energy dependence of valley polarization of the charge carriers across the defect. These findings inspire us to propose a compact electrostatically gated "valley valve" device, a critical component for valleytronics. 
J.-H. Chen, G. Aut\`es, N. Alem, F. Gargiulo, A. Gautam, M. Linck, C.   Kisielowski, O. V. Yazyev, S. G. Louie and A. Zettl
cond-mat.mes-hall cond-mat.mtrl-sci