Computational study of K2OsI6 double perovskite for spintronics, and thermoelectric applications

Abstract

This study explores the structural stability, electronic properties, and thermoelectric performance of the vacancy-ordered double perovskite K₂OsI₆ using the generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) approximation. The calculated tolerance factor ($t_f$ ≈ 0.927) and elastic constants confirm the structural stability of K₂OsI₆ in a cubic phase, while the elastic constants also highlight its ductile and anisotropic nature. The analysis of density of states and band structure revealed a direct band gap of 0.9 (1.3) eV at the GGA (mBJ) level of theory in the spin up channel. The half-metallic ferromagnetism is predicted to exhibit 100 % spin polarization at the Fermi level. Furthermore, the thermoelectric parameters such as electrical conductivity (σ), thermal conductivity (κ_e), Seebeck coefficient (S), power factor (PF), and figure of merit (ZT) were investigated. The thermoelectric parameters show n-type behaviour and a significant ZT value of 0.73. The findings suggest that the K₂OsI₆ may be a potential candidate for spintronics and thermoelectric applications.