First-principles insights into p magnetism in CaC and CaN ionic compounds

Density functional-pseudopotential calculations are employed for more understanding of the exchange interaction in the novel p ferromagnetic CaC and CaN compounds in the rock-salt, zinc-blende, wurtzite and NiAs structures. It is observed that the generalized gradient functional give rises to a half-metallic or nearly half-metallic electronic structure for these systems. Comparing the structural properties in the ferromagnetic and nonmagnetic states clarifies that the bonding properties are almost independent of the exchange interaction in these systems. It is observed that the interatomic exchange interaction in these systems is quite strong and controls the splitting of the spin resolved bond points. The non-local Hartree-Fock based exchange correction is found to enhance the half-metallic behavior of the systems while preserving their equilibrium volume and compressibility.