Oxygen-induced magnetic properties and metallic behavior of a BN sheet.

In this paper, an ab initio method has been employed to study the adsorption energies, electronic structures and magnetic properties of a BN sheet functionalized by an oxygen (O) atom. The adsorption process is typically exothermic, and some unusual properties can be revealed with different adsorption sites. The energy gap of the BN sheet narrows due to the strong hybridization between O and BN electronic states when the O locates above a BN bond or a nitrogen atom. Upon the adsorption of O above a B3N3 ring or a boron atom, the electrons of the O-adsorbed BN system are polarized, which gives rise to a magnetic moment of 2.0 μ(B). In this case, the Fermi level crosses the valence band, resulting in the O-adsorbed BN system being metallic. Furthermore, potential energy curve analysis shows that the magnetism and metallicity of the BN system can be modulated by the external temperature and pressure.