Computer based predictions of structural stability and systematic study of magneto-electronic and optical properties of Lead Free Halide Double Perovskites: Cs2 KXCl6 : X = Co and Ni

In this study, the structural stability, optoelectronic, and magnetic characteristics of lead-free halide double perovskites Cs2 KXCl6: X = Co and Ni were revealed and understood utilizing a rigorous and systematic investigation employing the density functional theory adopted in WIEN2k simulation software. The given double perovskites are stable in cubic structure having Fm-3 m symmetry, this stability was confirmed by optimized structural, satisfying criteria of mechanical stability and tolerance factor. The half-metallic ferromagnetic feature of materials is caused by unpaired electrons in the crystal field splitted d-orbitals of Co and Ni. The total magnetic moments of these double perovskites were computed, and the calculated results were 4 μB for Cs2 KCoCl6 and μB for Cs2 KNiCl6, with the transition metal atoms contributing the most. The fact that these double perovskites exhibit 100% spin polarization at the Fermi level suggests that they might be used in spintronics.