First-Principles Calculation of structural, electronic and magnetic properties of half-Heusler LiCaC and NaCaC compounds

The structural, electronic and magnetic properties of LiCaC and NaCaC compounds in half-Heusler structure have been studied using local density approximation (LDA) based on density functional theory (DFT). From the total energy calculation, it is found that the compounds LiCaC and NaCaC are stable in ferromagnetic phase. The spin-polarized electronic band structure and density of states of these compounds show that the minority spin channel has metallic nature and the majority spin channel has a semiconducting gap of 2.27 and 2.0 eV for LiCaC and NaCaC respectively, resulting in a stable half-metallic ferromagnetic (HMF) behavior with magnetic moment of 1 µB per formula unit. Analysis of density of states of these compounds indicates that the magnetic moment mainly originates from the strong spin-polarization of 2p like states of C and the hybridization between the C-2p like states and the Ca-3d like states. The robustness of half-metallicity against the lattice constant is also calculated. Presence of HMF in LiCaC and NaCaC compounds without any transition metal makes these compounds promising materials for spintronic applications.