Exchange interaction and Tc in alkaline-earth-metal-oxide-based DMS without magnetic impurities:: First principle pseudo-SIC and Monte Carlo calculation

The prospects of half-metallic ferromagnetism being induced by the incorporation of C atoms into alkaline-earth-metal-oxides are investigated by the first principle calculation. The origin of the ferromagnetism is discussed through the calculation of the electronic structure and exchange coupling constant by using the pseudo-potential-like self-interaction-corrected local spin density method. The Curie temperature (T-c) is also predicted by employing the Monte Carlo simulation. It is shown that by taking the electron self-interaction into account, the half-metallic ferromagnetism induced by C in the host materials is more stabilized in comparison with the standard local density approximation (LDA) case, and the C's 2p electron states in the bandgap become more localized resulting in the predominance of the short-ranged exchange interaction. While the ferromagnetism in MgO1-xCx,C, is stabilized due to the exchange interaction of the first-nearest neighbor pairs and might be suppressed by the anti-ferromagnetic super-exchange interaction at higher x, the ferromagnetism in CaO1-xCx, SrO1-xCx and BaO1-xCx is stabilized by both the first- and second-nearest neighbor pairs, and T-c monotonously increases with the C concentration.