Optical and pressure-induced investigations of double perovskite Ba₂TiMnO₆ from the first principles

Double perovskite (DP) compounds have been reported to possess many valuable properties and are considered excellent candidates for magnetocaloric applications, high-performing semiconductivity in optoelectronic devices, and photo(electro)chemical energy storage systems [1-4]. To explore the physical properties of double perovskite Ba₂TiMnO₆, we examined its optical and pressure dependence utilizing PBE-GGA and PBE-GGA+U exchange—correlation energy functionals. Following previous findings, DFT calculations revealed direct semiconducting band-gaps of 0.82, 0.98, and 1.27 eV, respectively [5]. Moreover, the optical properties show high dielectric constants, a robust light absorption coefficient in the UV energy range, and a significant optical conductivity of 6.53 × 105 cm−1, making Ba₂TiMnO₆ a promising candidate for high-performance perovskite solar cells in optoelectric applications. We identified that optical properties below 10 eV are mostly due to intraband and interband transitions of Mn-3d electrons. Employing the Projected Augmented Wave (PAW) method, we also studied the impact of pressure on crystal structure and density of states. Notably, near 8 GPa, there appears to be a structural distortion, accompanied by a sharp increase in the semiconducting gap.

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