title: Graphene bilayer with a twist: electronic structure.
abstract: We consider a graphene bilayer with a relative small angle rotation between the layers--a stacking defect often seen in the surface of graphite--and calculate the electronic structure near zero energy in a continuum approximation. Contrary to what happens in an AB stacked bilayer and in accord with observations in epitaxial graphene, we find: (a) the low energy dispersion is linear, as in a single layer, but the Fermi velocity can be significantly smaller than the single-layer value; (b) an external electric field, perpendicular to the layers, does not open an electronic gap.
authors.affiliation: CFP and Departamento de Física, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal.
authors.forename: J M B
authors.initials: JM
authors.lastname: Lopes Dos Santos
authors.forename: N M R
authors.initials: NM
authors.lastname: Peres
authors.forename: A H
authors.initials: AH
authors.lastname: Castro Neto