Cs<inf>2</inf>KMnCl<inf>6</inf>: A possible half-metallic double perovskite for spintronics

Materials with 100% spin polarisation, high-speed conduction electrons, high Curie temperatures, and ferromagnetic ground state are known for spintronics. Double perovskites (DPs) with these features are becoming popular nowadays. Herein, introducing another halide-based DP, we determined that Cs2KMnCl6 is a robust intrinsic 3d ferromagnetic half-metal with a 4 μB magnetic moment per unit cell. It exhibits the metallic band for the spin-up configuration, enabling their smooth transport, together with a massive gap of ∼4.51 eV for the spin-down states, thus protecting it from spin-flip transitions. The calculated structural and elastic stability criteria substantiate the stability of the cubic Cs2KMnCl6 double perovskite with a F m 3 ¯ m symmetry. The 3d states of Mn mainly contribute to the robust ferromagnetism above room temperature and show Tc ∼ 534 K. The different Fermi surface topologies within the Brillouin zone establish its conducting nature for up-spin channels and favor the spin-polarized transport. Moreover, the spin-polarized dielectric constant and absorption coefficient also evidenced the half-metallic characteristics. Therefore, our findings offer a novel DP system for investigating spintronic application.