Unveiling the half-metallic ferromagnetism and transport properties of LiFeX₃ (X = Cl, Br, I) perovskites for energy conversion and data processing devices

This research aims to examine the half-metallic ferromagnetic and transport response of LiFeX₃ (X = Cl, Br, I) by first-principles’ calculations. The stability of the studied ternary compounds in the ferromagnetic phase is established and supported by high energy emission related to the anti-ferromagnetic phase. The ductility is evidenced by Poisson and Pugh ratios surpassing cutoff limits (0.26 and 1.75), in addition phonon dispersion spectra confirm the thermodynamic stability of these materials. The negative value of formation enthalpy reveals that these materials are stable in ferromahnetic phase. The study of the electronic band structure is performed using TB-mBJ potential to clarify their half-metallic character. The DOS results reveal substantial participation from the p-state of X in valence and Fe 3d-state in the conduction band. Comparing the crystal field (ΔE_crystal) and the exchange energies (indirect Δx(Pd) and direct Δx(d)) sheds light on the crucial contribution of electronic spin in the ferromagnetic behavior. The total magnetic moment (4 µ_B) observed in the halide perovskites underscores their potential for spintronic applications. Besides, within the temperature range of 200–800 K, the thermoelectric parameters are computed and the increasing value of Seebeck coefficient and figure of merit with the rise of temperature demonstrate their potential in thermoelectric devices like thermoelectric generators.