Abstract
The ferromagnetic semiconductive nature of novel double perovskite (DP) ruthenates Ba2NdRuO6 and Ba2Er-RuO6 is recognized along with their structural, mechanical, optical, and thermoelectric properties. The structural optimization indicates that ruthenate DPs are stable in cubic Fm-3 m phase with a ferromagnetic character. Both compounds satisfy the criteria for cubic stability with tolerance factor (tau(G)) value of 0.92 / 0.95 and thermodynamical stability criteria with Delta H = -8.552 eV / -8.576 eV for Ba2Nd/ErRuO6 DPs, respectively. The LDA + U calculated band structures (BS) and density of states (DOS) exhibit the ferromagnetic p-type semiconducting nature with low band gaps (E-g). The Ru(5+ )and Nd3+/Er3+ atoms majorly contribute to the total magnetic moments (similar to 6 mu(B)) for both compounds. The optimal value of absorption in higher infrared, visible and ultraviolet energy range coupled with immense structural and mechanical stability show that these materials can be potentially used in solar energy harvesting devices and are suitable candidate for their application in replacing the silicon-based electronics and optical devices. Moreover, the figure of merit (ZT) values well above 0.7 within the whole temperature range of 300 - 800 K for both DPs show the material's great efficiency for thermoelectric (TE) devices. Highly asymmetric spin polarized semiconducting electronic bands and higher TE efficiency strongly supports the possible applications of these DPs for spintronic and energy harvesting devices.