Electric-dipole-induced universality for Dirac fermions in graphene

Phys Rev Lett. 2014 May 9;112(18):186603. doi: 10.1103/PhysRevLett.112.186603. Epub 2014 May 9.

Abstract

We study electric dipole effects for massive Dirac fermions in graphene and related materials. The dipole potential accommodates 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.