We study electric dipole effects for massive Dirac fermions in graphene and related materials. The dipole potential accomodates towers of infinitely many bound states exhibiting a universal Efimov-like scaling hierarchy. The dipole moment determines the number of towers, but there is always at least one tower. The corresponding eigenstates show a characteristic angular asymmetry, observable in tunnel spectroscopy. However, charge transport properties inferred from scattering states are highly isotropic.
Categories: cond-mat.mes-hall
