Synthetic ferromagnetic nitrides: First-principles calculations of CaN and SrN

Encouraged by recent experimental facts of synthesizing materials which do not exist in nature, we introduce a type of ferromagnets, CaN and SrN, which have been proposed by first-principles calculations. These are half-metallic ferromagnets and they have magnetic moments of 1 mu(B) per chemical formula unit. Out of typical structures of binary compounds we have calculated, the rocksalt structure is the most stable form for both CaN and SrN. The majority of the magnetic moment of these compounds originates from the nitrogen sites since the p states of nitrogen are spin polarized. The mechanism of the ferromagnetism is discussed. Their formation energies have been calculated and the results show that it should be feasible to synthesize these materials. The structural stability of CaN has been confirmed by performing first-principles molecular dynamics simulations. We propose a synthesis process for CaN using the high pressure and temperature environment.