Predicting and understanding the structural stability, origin of half-metallic magnetic nature, and study of opto-electronic properties of Cs2KXCl6: X = Ti and V double perovskites

A succinct summary of various physical characteristics of halide double perovskites Cs2KXCl6: (X = Ti and V) has been summarized using Density Functional Theory (DFT), as applied in WIEN2k simulation code. These material's stability in Fm-3 m cubic symmetry is confirmed by structural optimization, tolerance factor and elastic parameters. The electronic band structures and density of states calculated using GGA and GGA+mBJ show that these materials are semiconducting in spin down channels. The crystal field splitting of d-orbitals is used to explain the semiconducting ferromagnetic nature of these Ti-and V-based halide double perovskites. The ferromagnetic character of these double perovskites is suggested by the optimization and asymmetric DOS across Fermi level. We have also discussed about the origins of half-metallic bandgap and magnetism. The total magnetic moments of the Ti and V-based double perovskites are 1 mu B and 2 mu B, respectively, with the transition metal atoms (Ti/V) accounting for the major contributions. At the Fermi level, these double perovskites have 100% spin polarization, indicating that they could be used in spintronics.