Structural, elastic, mechanical, electronic, magnetic, thermoelectric and thermodynamic investigation of half metallic double perovskite oxide Sr2MnTaO6

Abstract

Abstract Experimental lattice constant has been used for theoretical predictions on structural, elastic, mechanical, electronic magnetic thermoelectric and thermodynamic properties of Sr2MnTaO6 double perovskite oxide within well-known ab-initio density functional theory. Optimized lattice constant has been employed for obtaining spin involved electronic structure results within generalized gradient approximation (GGA), Hubbard approximation (GGA + U) and modified Becke Johnson approximation (mBJ). Electronic results show half-metallic nature with majority spin channels as metallic and minority spin channels as semi-conducting. Magnetic moment calculated within GGA + U was found equal to 4 µb. Calculated large value of Bulks modulus (B) and Young modulus (Y) characterize it as hard and stiffer material. Pugh ratio (B/G) and Cauchy pressure (C12–C44) portray its brittle nature. Using Boltztrap code we have calculated the variation of electrical conductivity (σ/τ), Seebeck coefficient (S), electronic thermal conductivity (k/τ) and Power factor (PF) in both spin channels. (σ/τ) is found to have decreasing nature in spin up states and increasing nature in spin down states, hence confirms the metallic nature in spin up states and semi-conducting in spin down states. Seebeck coefficients (S) reveal the presence of positive charge carriers in spin up states and negative in spin down states. The computed value of total power factor was found to be 1.99 × 1012 WK−2 m−1 s−1 at 1000 K. Furthermore, we have computed pressure and temperature dependent thermodynamic parameters for this compound in the temperature range of 0 K to 1000 K and pressure range of 0 GPa to 18 GPa with a step size of 3 GPa.