Theory of the valleyvalve effect in graphene nanoribbons
Abstract
A potential step in a graphene nanoribbon with zigzag edges is shown to be an intrinsic source of intervalley scattering—no matter how smooth the step is on the scale of the lattice constant a . The valleys are coupled by a pair of localized states at the opposite edges, which act as an attractor and/or repellor for the edge states propagating in valley K/K^{'} . The relative displacement ∆ along the ribbon of the localized states determines the conductance G . Our result G=(e^{2}/h)[1cos(Nπ+2π∆/3a)] explains why the “valleyvalve” effect (the blocking of the current by a pn junction) depends on the parity of the number N of carbon atoms across the ribbon.
 Publication:

Physical Review B
 Pub Date:
 May 2008
 DOI:
 10.1103/PhysRevB.77.205416
 arXiv:
 arXiv:0712.3233
 Bibcode:
 2008PhRvB..77t5416A
 Keywords:

 73.20.Fz;
 73.23.b;
 73.40.Gk;
 73.63.Nm;
 Weak or Anderson localization;
 Electronic transport in mesoscopic systems;
 Tunneling;
 Quantum wires;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 5 pages, 6 figures, v3 added more numerical data and an appendix with details of the calculation