Valley polarized transport in graphene cross-junctions

Valley polarized transport was studied in graphene cross junctions consisting of a bilayer graphene device region connected to 4 monolayer graphene leads. Electrons injected from the armchair leads to the zigzag leads can be valley polarized in a range of Fermi energies. The valley polarization is produced by quantum interference and the Fano resonance effect in the device region. We also studied the dependence of the valley polarization on the dimensions of the junction and a vertical electric field applied to the device region. The valley polarization depends sensitively on the electric field, which enables us to control the valley polarization electrically.