First-principles study of the electronic and magnetic properties of 4-8 line-defect-embedded BN sheets decorated with transition metals

Very recently, the 4-8 line defects (LDs), containing homoelemental B-B and N-N bonds at the squares and octagons, have been observed in BN sheets under electron-beam irradiation. Inspired by the experiment, a first-principles study on these 4-8 LD-embedded BN sheets and the doping effects of transition metal (TM) atoms was conducted. It was found that the homoelemental bonds induce defect states in the band gap of BN sheets, which markedly reduce the gap value by 38%. The line defect binds the foreign TM atoms strongly, which can form one-dimensional TM chains in the sheets. Consequently, diverse electronic and magnetic properties are induced into BN sheets: the Cr- and Ni-chain dopings bring a quasi-spin-gapless semiconducting feature, the Fe- and Co-chain dopings cause a ferromagnetic semiconducting behavior, and the Mn one even transforms the sheets into antiferromagnetic semiconductors. The studies demonstrate that these TM-chain-doped BN sheets are potential candidates for spintronics and nanodevices.