Electronic and magnetic properties of triangular graphene quantum rings

Abstract

Electronic and magnetic properties of triangular graphene rings potentially fabricated using carbon nanotubes as masks are described as a function of their size and width. The electronic properties of the charge neutral system are calculated using tight-binding method and interactions are treated using the mean-field Hubbard model. We show that for triangular quantum dots with a triangular hole, the magnetic properties are determined by the width of the ring, leading to ferromagnetic corners and antiferrimagnetic sides. The electronic properties of gated graphene quantum rings as a function of additional number of electrons or holes are described by a combination of tight-binding, Hartree-Fock, and configuration interaction methods. The outer edge is found to be maximally spin polarized for almost all filling factors while the evolution of the excitation gap as a function of shell filling shows oscillations as a result of electronic correlations.