Carbon p-electron induced magnetic ordering in Zn-implanted 6H–SiC: experimental observation and theoretical calculation
We observed clear ferromagnetic ordering in 6H–SiC crystal bombarded with zinc ions, and presented a detailed investigation of magnetic properties in this sample. The magnetization of Zn-implanted 6H–SiC fell and rose with annealing temperature from 500 °C to 1100 °C. Meanwhile, amount of oxygen penetrated lattices and combined with Si-bonds after 1100 °C annealing. Using ab initio calculations based on density functional theory, we confirm that Zn ions play a role in the origin of ferromagnetism, while the localized moment is mainly comes from C2p electrons surrounding the foreign particle (which is Zn in this work). Silicon vacancies can provide localized moment about 2.0 μB/VSi and form stable ferromagnetic interaction at room temperature. Oxygen may facilitate this coupling and no need of VC-mediation any more. The calculations are consistent with experimental results. We concluded that the dangling C2p bonds are fundamental cause of magnetic ordering in whatever microstructures in 6H–SiC crystal. The type of foreign impurities is not crucial factor for the magnetic origin in such carbon-based materials.