Understanding the role of 5d electrons in ferromagnetism and spin-based transport properties of K2W(Cl/Br)6 for spintronics and thermoelectric applications

Abstract

In this article, we have systematically investigated the structural, electronic, magnetic, and spin-based thermoelectric properties of K₂W(Cl/Br)₆ by first-principles calculation. The obtained negative formation energy confirmed the thermodynamic stability of K₂W(Cl/Br)₆, while the tolerance factor calculation showed their cubic phase stability. In addition, we have estimated the elastic constants which confirmed the mechanical stability of K₂W(Cl/Br)₆. Further, the spin-polarized band structure and density of states calculations revealed the half-metallic nature with high Curie temperature (T_c) values of 613 K and 597 K for K₂WCl₆ and K₂WBr₆, respectively. Moreover, we have studied the temperature variation of thermoelectric properties such as k_l, σ, k_e, S, PF, and ZT. Such results showed that higher ZT values for spin-down channels are obtained from ultra-low k_e, and high PF. Therefore, K₂W(Cl/Br)₆ are viable thermoelectric and spintronic materials.