Consequences of Tuning Rare-Earth RE(3+)-Site and Exchange–Correlation Energy U on the Optoelectronic, Mechanical, and Thermoelectronic Properties of Cubic Manganite Perovskites REMnO(3) for Spintronics and Optoelectronics Applications

[Image: see text] Both rare-earth SmMnO(3) and EuMnO(3) compounds that belong to transition-metal-based manganite perovskites REMnO(3) have been studied deeply in this paper. The structural, elastic, optoelectronic, magnetic, mechanical, and thermoelectronic properties of cubic SmMnO(3) and EuMnO(3) compounds have been computed using the full-potential linearized augmented plane-wave (FP-APLW) method in the frame of density functional theory (DFT). To compute the ground-state energy, the effect of exchange–correlation potential was treated via the application of generalized gradient approximation within Perdew, Burke, and Ernzerhof (PBE-GGA) plus its corrected method (GGA + U). The spin-polarized results of band structures, density of states (DOS), and magnetic moments show that SmMnO(3) and EuMnO(3) have ferromagnetic half-metallic (FM-HM) behavior. Optical responses of dielectric function (ε(ω)) are explained by computing the real ε(1)(ω) and imaginary ε(2)(ω) parts of ε(ω), refractive index n(ω), extinction coefficient k(ω), absorption coefficient α(ω), optical conductivity σ(ω), reflectivity R(ω), and energy loss function L(ω) using GGA and GGA + U. Also, we computed and discussed the thermoelectronic properties of SmMnO(3) and EuMnO(3), including Seebeck coefficient (S), holes and electrons charge carrier concentration (n), electrical conductivity (σ/τ), power factor (S(2)σ/τ), figure of merit (ZT), thermal conductivity (κ), and specific heat capacity (C(V)), as a function of temperature (T), using GGA and GGA + U methods based on BoltzTrap scheme. The present results confirm the perfect mechanical and thermal stability of two perovskites which make SmMnO(3) and EuMnO(3) promising materials for spintronics, optoelectronics, high-temperature, and other related applications.