The adhesion of graphene on slightly lattice-mismatched surfaces, for instance, of hexagonal boron nitride (hBN) or Ir(111), gives rise to a complex landscape of sublattice symmetry-breaking potentials for the Dirac fermions. Whereas a gap at the Dirac point opens for perfectly lattice-matched graphene on hBN, we show that the small lattice incommensurability prevents the opening of this gap and rather leads to a renormalized Dirac dispersion with a trigonal warping. This warping breaks the effective time-reversal symmetry in a single valley. On top of this an additional set of massless Dirac fermions is generated, which is characterized by a group velocity that is about half the one of pristine graphene. © 2012 American Physical Society.

Graphene on incommensurate substrates: Trigonal warping and emerging Dirac cone replicas with halved group velocity

Ortix, Carmine;
2012-01-01

Abstract

The adhesion of graphene on slightly lattice-mismatched surfaces, for instance, of hexagonal boron nitride (hBN) or Ir(111), gives rise to a complex landscape of sublattice symmetry-breaking potentials for the Dirac fermions. Whereas a gap at the Dirac point opens for perfectly lattice-matched graphene on hBN, we show that the small lattice incommensurability prevents the opening of this gap and rather leads to a renormalized Dirac dispersion with a trigonal warping. This warping breaks the effective time-reversal symmetry in a single valley. On top of this an additional set of massless Dirac fermions is generated, which is characterized by a group velocity that is about half the one of pristine graphene. © 2012 American Physical Society.
2012
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4706808
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