Tunable electronic structures and magnetic properties of zigzag C3N nanoribbons

On the basis of first principles methods, we systematically investigate the electronic structures and magnetic properties of zigzag C3N nanoribbons (ZCNNRs) with ribbon widths (N) from 4 to 12. The unsaturated ZCNNRs are predicted to be magnetic metals or magnetic nearly half-metals depending on the ribbon width. The magnetic moments of ZCNNRs mainly result from the edged C atoms. The magnetic interactions of the narrower ribbon widths between the opposite edges are sensitive to the tensile strains, and the magnetic stability of the wider nanorribons can be effectively improved by applying the tensile strains. The mechanism of magnetism in ZCNNRs can be well understood through the Stoner criterion. In addition, the effect of H passivation is also explored. The edge magnetism disappears after H passivation. For even N, the H-passivated ZCNNRs are semiconductors and the band gap decreases with the enlargement of ribbon width. Moreover, the H-passivated ZCNNRs undergo an indirect-to-direct band gap transition at N = 12. For odd N, the ribbons exhibit metallicity due to the half-filled bands across the Fermi level at π/2a.