First-principles calculations were used to investigate the possible magnetism induced by different concentrations of nonmagnetic impurities and vacancies in a BN sheet. Atoms of Be, B, C, N, O, Al and Si were used to replace either B or N in the system as impurities. Attention was paid to the changes in the density of states as well as the extent of the spatial distribution of the defect states, the possible formation of magnetic moments, the magnitude of the magnetization energies, and finally the exchange energies due to the presence of these defects. It was shown that the magnetization energy tends to increase as the concentration of the defects decreased in most of the defect systems, which implies a definite preference for finite magnetic moments. The calculated exchange energies were in general tiny but not completely insignificant for two of the studied defect systems, i.e., one with O impurities substituting for N and the other with B vacancies.

Ab initio Studies of Possible Magnetism in a BN Sheet by Nonmagnetic Impurities and Vacancies. R.F.Liu, C.Cheng: Physical Review B, 2007, 76[1], 014405 (8pp)