First principles study on the structural, electronic, mechanical and optical properties of Pb-free double perovskites M2FeMnO6 (M = Rb, Cs)

The researchers are looking for efficient smart materials to cope with the energy crisis. In this regard, double perovskites are extensively studied for various technological advantages. In the present work, we investigated the structural, electronic, optical, and elastic properties of double perovskites M2FeMnO6 (M = Rb, Cs) using the WIEN2k package within density functional theory (DFT). The structural properties reveal that both compounds are stable and can be fabricated experimentally. The electronic study indicates that both compounds possess a metallic nature in spin up configuration while in the spin down configuration these materials are insulators overall they possess half metallic nature. The elastic parameters indicates that these compounds are mechanical stable. Furthermore, the ductile and anisotropic nature is conformed from the computed elastic constant obtained through IR-Elast package. Optical parameters such as dielectric constants, optical absorption, optical conductivity, and optical reflectivity are studied in the range of 0 to 40 eV energy range. From the study of these compounds, we recognize that these materials can be potential applicants for spintronic and optoelectronic devices.