Electronic structure and half-metallic property of Si3CaC4

The electronic structures and magnetic properties of Si3CaC4 in zinc-blende phase has been studied by employing the first-principles method based on density functional theory (DFT). The calculations predict stable ferromagnetic ground state in Si3CaC4, resulting from calcium substitution for silicon. The calculated total magnetic moment is 2.00 mu(B) per supercell, which mainly arises from the Ca and neighboring C atoms. Band structures and density of states studies show half-metallic (HM) ferromagnetic property for Si3CaC4. The ferromagnetic coupling is generally observed between the Ca and C atoms. The ferromagnetism of Si3CaC4 can be explained by the hole-mediated double exchange mechanism. The sensitivity of half-metallicity of Si3CaC4 as a function of lattice constant is also discussed, and the half-metallicity can be kept in a wider lattice constant range.