A first-principles investigation of the structural, optoelectronic, elastic and thermal properties of the p-type half-metallic ferromagnetic perovskites BaFeX3(X = Cl, Br, I)

The half-metallic nature of the metal halide perovskites BaFeX3 (X = Cl, Br,I) and their physical properties were studied using Spin-polarised Density Functional Theory calculations. For each structure, ferromagnetic, antiferromagnetic and non-magnetic calculation were performed and the ferromagnetic phase was found to have the lowest energy. The calculated band structures in addition to the electronic density of states confirmed half-metallicity, where the perovskites showed semiconducting nature in the spin up channel and metallic in spin-down channel. The optical properties are calculated and strong absorption in the UV range was seen and the mechanical properties demonstrated mechanical stability with ductile behaviour for all perovskites. The specific heats(at constant volume) of all of the studied perovskites levelled off to about 245 JK(-1) mol(-1) at high temperatures. The Seebeck coefficient was also calculated as a function of temperature and found to be positive for all the structures which confirm them to be p-type materials. These perovskites are therefore suited for thin film fabrication and bulk single crystals for applications such as UV photodetectors and energy harvesting, in addition to spintronics applications