Energy gaps, magnetism, and electric field effects in bilayer graphene nanoribbons

Abstract

Using a first principles density functional electronic structure method, we study the energy gaps and magnetism in bilayer graphene nanoribbons as a function of the ribbon width and the strength of an external electric field between the layers. We assume AB (Bernal) stacking and consider both armchair and zigzag edges and two edge alignments distinguished by a 60${}^o$ rotation of one layer with respect to the other. Armchair ribbons exhibit three classes of bilayer gaps which decrease with increasing ribbon width. An external electric field between the layers increases the gap in narrow ribbons and decreases the gap for wide ribbons, a property which can be understood semi-analytically using a $\pi$-band tight-binding model and perturbation theory. The magnetic properties of zigzag edge ribbons are different for the two different edge alignments, and not robust for all exchange-correlation approximations considered. Bilayer ribbon gaps are sensitive to the presence or absence of magnetism.

8 pages, 8 figures (contents and figures changed)

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Cited by in corpus (9)

• The electronic properties of bilayer graphene
• Robustness of edge states in graphene quantum dots
• Electronic transport through bilayer graphene flakes
• Transmission through a boundary between monolayer and bilayer graphene
• The catalytic potential of high-k dielectrics for graphene formation
• Disorder-induced tail states in a gapped bilayer graphene
• Electronic conductance of twisted bilayer nanoribbon flakes
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• Giant Magnetoresistance in Bilayer Graphene Nanoflakes