Theory of the valley-valve 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/repellor for edge states propagating in valley K/K'. The relative displacement Delta along the ribbon of the localized states determines the conductance G. Our result G=(e^{2}/h)[1-\cos(Nπ+2πΔ/3a)] explains why the ``valley-valve'' effect (the blocking of the current by a p-n junction) depends on the parity of the number N of carbon atoms across the ribbon.

5 pages, 6 figures, v3 added more numerical data and an appendix with details of the calculation

References in corpus (8)

• Energy Band Gap Engineering of Graphene Nanoribbons
• Valley filter and valley valve in graphene
• Graphene Nano-Ribbon Electronics
• Electronic States of Graphene Nanoribbons
• Selective transmission of Dirac electrons and ballistic magnetoresistance of \textit{n-p} junctions in graphene
• Conductance quantization in mesoscopic graphene
• Coulomb blockade in graphene nanoribbons
• Valley-isospin dependence of the quantum Hall effect in a graphene p-n junction

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