Optoelectronic and structural properties of bulk cubic perovskite RbTaO3 and surface (0 0 1) for optoelectronic and spintronics applications

We used first-principles density functional theory (DFT) to study the optical, electronic, and structural properties of RbTaO₃ cubic perovskite in both bulk and surface (0 0 1) forms. The RbTaO₃ bulk system exhibited semiconducting behaviour with a band gap (E_g) of 2.20 eV. It showed weak reflectivity, excellent optical conductivity, and high absorption of incident energetic photons, indicating its potential for optoelectronic applications. For the surface (0 0 1), two RbO and TaO₂ terminations were constructed. We calculate the atomic displacement (ΔZ) and surface energy (E_surf) for both terminations. The RbO- and TaO₂-(0 0 1) terminated surfaces appeared half-metallic ferromagnetic (HMF) with a spin magnetic moment of integer value 1.00 μ_β and fully spin polarization (SP) 100 %. The E_g for RbO- and TaO₂-terminations were 2.60 eV and 2.30 eV, respectively, suggesting their potential for spintronics. We also analysed and compared the optical properties and atomic populations (Q) and their variation (ΔQ) for (0 0 1)-RbTaO₃ terminations with the bulk system.