Role of vacancies in the magnetic and electronic properties of SiC nanoribbons: An<i>ab initio</i>study

Abstract

Using ab initio calculations based on density functional theory, we investigate the effects of vacancies on the electronic and magnetic properties of zigzag SiC nanoribbons (Z-SiCNR). Single (${V}_{\mathrm{C}}$ and ${V}_{\mathrm{Si}}$) and double (${V}_{\mathrm{Si}}{V}_{\mathrm{Si}}$ and ${V}_{\mathrm{Si}}{V}_{\mathrm{C}}$) vacancies are observed to induce magnetism in Z-SiCNRs. The presence of a single ${V}_{\mathrm{Si}}$ does not affect the half-metallic behavior of pristine Z-SiCNRs; however, a single ${V}_{\mathrm{C}}$ leads to a transition from half-metallic to metallic behavior in Z-SiCNRs due to the edge Si $p$ orbitals and the atoms surrounding the vacancy. The interactions of vacancies with foreign impurity atoms (B and N) are also investigated, and it is observed that ${V}_{\mathrm{Si}}{N}_{\mathrm{C}}$ not only suppresses the oscillatory type magnetism of ${V}_{\mathrm{Si}}{V}_{\mathrm{C}}$ but also retains the half-metallic character of the pristine Z-SiCNRs. The defect formation energies of vacancies can be reduced by substitutional B and N atoms. We believe that ferromagnetism is expected if Z-SiCNRs are grown under suitable conditions.