Half-metallic sp-electron ferromagnets in rocksalt structure: The case of SrC and BaC

First-principles calculations are employed to study the structural and magnetic properties of SrC and BaC in four different phases: rocksalt, CsCl, zinc blende, and NiAs. The obtained results indicate that both compounds show half-metallic behavior in all phases except the CsCl-type structure. Among them the rocksalt structure is found to be the most stable one with a robust half-metallic characteristic with respect to the lattice compression and expansion. The magnetic phase transition temperature Tc of the rocksalt phase is calculated employing both the mean-field approximation and the random-phase approximation. The predicted Tc values of both compounds are considerably above room temperature.