Cation-vacancy induced intrinsic magnetism in GaN and BN was investigated by employing density-functional theory based electronic structure methods. The strong localization of defect states favours spontaneous spin polarization and local moment formation. A neutral cation vacancy in GaN or BN led to the formation of a net moment of 3µB with a spin-polarization energy of about 0.5eV at the low density limit. The extended tails of defect wave functions, on the other hand, mediate surprisingly long-range magnetic interactions between the defect-induced moments. This duality of defect states suggested the existence of defect-induced or mediated collective magnetism in these otherwise non-magnetic sp systems.

Defect-Induced Intrinsic Magnetism in Wide-Gap III Nitrides. P.Dev, Y.Xue, P.Zhang: Physical Review Letters, 2008, 100[11], 117204