First-principles calculations to investigate role of 4d electrons spin (Mo/Tc) in half metallic ferromagnetism, and thermoelectric characteristics of Rb2(Tc, Mo)X6 (X =Cl, Br)

Abstract

The absolute spin polarization, stable structures, and non-toxic nature of vacancy-ordered double perovskites (DPs) make them merging materials for spintronic. Therefore, in the present study, the role of 4 d electrons of Mo/Tc has been focused comprehensively to monitor the ferromagnetism in Rb2(Tc, Mo)X6 (X = Cl, Br). The electronic and magnetic behaviors have been analyzed by modified Back and Johnson potential and thermoelectric effect by BoltzTrap code. The tolerance and octahedral factor show the existence of structures, while formation energy calculations ensure thermodynamic stability. The density of electron states at the Fermi level and the Heisenberg model report the spin polarization and Curie temperature. The density of states exposed half-metallic ferromagnetism and the transition of electrons spin to endorse the exchange mechanism. The control of ferromagnetism by electron functionality has been analyzed regarding exchange energies, crystal field energies, double exchange model, exchange constants, and hybridization process. Furthermore, shifting a magnetic moment from Mo/Tc to Rb and Cl/Br sites dominates the ferromagnetism due to the exchange of electrons spin instead of magnetic clusters. Finally, the Seebeck coefficient, conductivity of electrons, and power factor have discussed the thermoelectric effect on spin functionality and thermoelectric performance.