Abstract
In this paper, we present results of a comprehensive systemic study of the crystal, electronic and magnetic structures on two members of Ru-based ordered double perovskite oxides Ba2XRuO6 (X = V, Cr). For the corporate compound, the analysis of density of states (DOS) results suggests that the 3d-t(2g) orbital filling plays a major role in governing the conduction mechanism in these systems. The DOS and magnetic results show that Ba2XRuO6 exhibits half-metallic (HM) nature as X = V, where the electronic structure of (Ba2VRuO6)-Ru-III-O-v with 3d-t(2g)(2) behaves like that of HM ferrimagnetic (FI), switches to compensate FI insulating behavior as X = Cr, with an extra electron filled 3d-t(2g)(3) in (Ba2CrRuO6)-Ru-III-O-v. We find, on consideration of electron correlation (LSDA+U) and spin-orbital coupling (SOC) effects that the electronic structure of Ba2XRuO6 takes a HM nature, whereas it is completely transformed to insulating nature once an extra electron filled the 3d-t(2g) orbitals in X = Cr case. Such tuning is accompanied by spin-state hopping of one electron from half-filled spin-state in Ru-v (t(2g)(3) e(g)(0)) to two and three occupied spin-state in V-III (t(2g)(2)e(g)(0)) and Cr-III (t(2g)(3)e(g)(0), respectively. The charge distribution results show that this extra electron occupies chiefly the spin-down of conduction orbitals and plays a major role in determining the electronic and magnetic structures of Ba2XRuO6 system. (C) 2017 Elsevier B.V. All rights reserved.