Carbon-doped zigzag boron nitride nanoribbons with widely tunable electronic and magnetic properties: insight from density functional calculations

First-principles calculations within the local spin-density approximation have been used to investigate the electronic and magnetic properties of carbon chain-doped zigzag born nitride nanoribbons (ZBNNRs). Our results indicate that doped half-bare ZBNNRs with an H-passivated B edge and a bare C edge generally have a spin-polarized ground state with the ferromagnetic spin ordering localized at the C edge, independent of the doping concentration and the ribbon width. In particular, doped half-bare ZBNNRs for all widths may produce half-semiconducting -> half-metallic -> metallic behavior transitions without an external electric field as the doping proceeds gradually from the N edge to the B edge. The breakage of the symmetric spin distribution in the bipartite lattice and the coexistence of the edge state and the border state arising from charge transfer in these doped ZBNNRs are responsible for their tunable electronic and magnetic properties.