Divacancies in graphitic boron nitride sheets

Spin-polarized density functional theory has been used to study the properties of seven kinds of divacancies in graphitic boron nitride sheets. We find that some divacancies are magnetic and the symmetry of the sheets is broken by the distortion of atoms which are close to the vacancies. According to the formation energies, the neighboring boron and nitrogen vacancy pair is the most likely to form. Our calculations demonstrate that the divacancies can induce fundamental changes in the electronic properties of the sheet, making semiconducting–to–half-metallic transitions occur. The results can be used to customize the spintronics devices.