Half metallic ferroamgnetism, and transport properties of vacancy ordered double perovskites Rb2(Os/Ir)X6 (X = Cl, Br) for spintronic applications

Abstract

The defected double perovskites, being non-toxic, stable, and capable to exhibit both spin-up (↑) and spin-down (↓) polarizations, are attractive for spintronic devices. In the present article, the role of 5d-electrons of Os and Ir to control the magnetic characteristics of Rb2(Os/Ir)Cl/Br6 is addressed. The structural and magnetic characteristics are investigated using PBEsol-mBJ functional, while thermoelectric behaviors are studied using BoltzTrap code. The computed tolerance factors (0.95/0.98, 0.94/0.96) and formation energies (−2.0/-1.65eV, −1.70/-1.10eV) confirm the structural and thermodynamic stabilities, respectively. The examination of band structures and density of states have revealed half-metallic ferromagnetic nature, which is further discussed in terms of double exchange model, exchange constants and exchange energies. The presented calculations indicate that underlying hybridization process, exchange energy, and crystal field energy induce ferromagnetism due to electron spin. Furthermore, thermal, and electrical conductivities, power factor, and Seebeck coefficients are computed and discussed to understand the thermoelectric applications.