Electronic structure and magnetism in M(=IA, IIA)C compounds with the   rocksalt structure
  Electronic structures of MC where M is the alkali and alkaline earth metals with the rocksalt structure are calculated by full potential density functional codes. We find that the spin magnetic moment in the compounds is mainly contributed by the spin polarized p-orbitals of carbon. The large distance between the carbon makes the p-orbitals localized, which induces magnetic instability according to the Stoner criterion. The electronic structure can be mapped to the rigid band model. SrC, BaC and RaC are half-metals, while KC, RbC and CsC are magnetic semiconductors 
Wenxu Zhang, Zhida Song, Bin Peng, Wanli Zhang
cond-mat.mtrl-sci