Ab-initio prediction of structure stability, electromagnetic, optical and thermoelectric behavior of orthorhombic LaXO₃ (X= Cr, Mn, Fe): For device application

In this paper, theoretical calculations for electronic band structure, the density of states, the optical and thermoelectric response of orthorhombic LaXO₃ (X = Cr, Mn, Fe) compounds are calculated. The Full Potential Linearized Augmented Plane Wave plus local orbital (FP-LAPW + lo) method is used in the context of density functional theory. Band gaps of three compounds are determined using Wu Cohen Generalized Gradient approximation with additional U potential (WC-GGA + U). Ferromagnetism is observed due to strong p-d hybridization and is justified by observed magnetic moments across individual atoms and at interstitial regions, and exchange constants are also reported. Optical properties are explained by calculating real and imaginary parts of the dielectric function, refractive index (n), extinction coefficient (k), reflection coefficient (R), the absorption coefficient (α), and energy loss spectrum (L). High value of dielectric constant, very small reflectivity and lower energy loss factor in, visible to ultraviolet region favours them for optoelectronic devices. We also computed the thermoelectric properties, including Seebeck coefficient, thermal and electrical conductivity and power factor as a function of temperature by combining results from DFT and Boltzmann transport theory. The phonon dispersion curve shows the stability of the current structures.