Dependence of Atomic Arrangement on Length of Flat Bands in Zigzag BC2N Nanoribbons

Abstract

We theoretically study the electronic properties of BC2N nanoribbons with zigzag edges using a tight binding model. We show that the zigzag BC2N nanoribbons have the flat bands and edge states when atoms are arranged as B-C-N-C along the zigzag lines. The length of the flat bands in the wavevector space depends on the atomic arrangement. This property can be explained by the deviation of the linear dispersion of the BC2N sheet from K point of the honeycomb lattice. The charge distributions in the edge states depend on the atomic arrangement. We also show that the charge distribution of the edge states in zigzag BC2N nanoribbons where the outermost sites are occupied with B and N atoms is different from those in conventional graphene zigzag edge. Such charge distribution causes different magnetic structures. We investigate the magnetic structure of BC2N nanoribbons with zigzag edges using the Hubbard model within a mean field approximation. At the zigzag edge where the outermost sites are occupied with B and N atoms, ferromagnetic structure appears when the site energies are larger than the on-site Coulomb interaction.