Ferromagnetic and half metallic properties of BaFeO₃ and CaFeO₃ for spintronic applications

First-principle calculations were conducted using the Wien2k code with the GGA, mBJ-GGA, and PBE0 (HSE06) functionals. The optimized lattice constants for the cubic unit cells of CaFeO₃ and BaFeO3 closely match the experimental values of 3.77 Å and 3.971 Å, respectively. The band structures and densities of states obtained with the mBJ-GGA method, along with the integer magnetic moment of 4 µB per unit cell, confirm the half-metallic nature of BaFeO₃ and CaFeO₃ in the spin-up channel. Both compounds, characterized by high symmetry, are more stable in the ferromagnetic half-metallic phase. For mBJ-GGA and YS-PBE0(HSE06) functionals, the materials under study are spin-gapless semiconductors. Hybridization of O-2p orbital with Fe-3d state in the upper valence band for spin-upmakes BaFeO₃and CaFeO₃as metallic materials. BaFeO₃ and CaFeO₃ exhibit large absorption coefficient 350 × 10⁴ cm^-1 and 500 × 10⁴ cm^-1 in the ultraviolet range, which can be attributed to the infrared phonon mode. The observed refractive index below 1 at the ultraviolet energy is a sign that these materials become superluminal. Furthermore, phonon dispersion calculations revealed the absence of imaginary frequencies across the Brillouin zone, confirming the dynamical stability of both perovskites and reinforcing their suitability for spintronic and optoelectronic applications.