Exploring half-metallicity and high-temperature optoelectronic potential of FrTiX3 (X = Cl, Br, I) compounds: A first-principles study

The discovery of half-metallicity in transition metal-based halide perovskites opens an exciting pathway in spintronic applications. This study employs first-principles density functional theory (DFT) using the GGA functional within the Vienna Ab-initio Simulation Package (VASP) to investigate the structural, electronic, optical, elastic, and thermal properties of FrTiX 3 (X = Cl, Br, I) . These materials show cubic symmetry and remarkable half-metallic behavior, characterized by metallic nature in one spin channel and insulating or semiconducting nature in the other spin channel with an indirect band gap of 4.44 eV, 3.67 eV, and 2.72 eV for FrTiCl 3 , FrTiBr 3 , and FrTiI 3 , respectively. The density of states shows 100% spin polarization at the Fermi level, and ferromagnetic nature with a total magnetic moment of 2.0 μ B for each material, indicating strong potential for spintronics device applications. With high melting points ranging from 729.1 K to 839.8 K, strong optical absorption and optical conductivity in the UV and EUV regions, these materials are promising candidates for advanced high-temperature optoelectronics. Elastic analysis confirms their mechanical stability, with significant shear and bulk moduli, and the ductile nature makes them suitable for various thin film applications. The thermoelectric response shows a positive Seebeck coefficient (23.19 μ V/K, 32.85 μ V/K and 49.73 μ V/K, respectively), showing the investigated materials are p-type in nature. Finally, the dynamic stability is confirmed by phonon dispersion calculations. Utilizing the unique properties of radioactive Francium and Titanium, this study opens new channels for developing advanced materials with potential applications in spintronic and optoelectronic technologies. • Half-metallic FrTiX 3 (X= Cl, Br, I) perovskites with 100% spin polarization at the Fermi level. • Ferromagnetic with 2.0 μ B moment with indirect band gaps of 2.72 to 4.44 eV. • Strong UV/EUV absorption with high melting points (729–840 K) for optoelectronics. • Mechanically and dynamically stable with a ductile nature. • Positive Seebeck coefficient, p-type materials.