title: Stabilization of ferromagnetic ordering in cobaltite double perovskites of La₂CoIrO₆ and La₂CoPtO₆.
abstract: We investigated the local electronic structure and magnetic properties of the cobaltite double perovskites La2CoIrO6 and La2CoPtO6 using Co L2,3-edge x-ray absorption spectroscopy and x-ray magnetic circular dichroism. Despite similarity in the local electronic structure (Co(2+) high-spin states) as well as in the crystal structure (P2(1)/n), only La2CoIrO6 exhibits substantial orbital and spin magnetic moments of Co(2+), whereas they are much weaker in the case of La2CoPtO6. This composition dependence is consistent with the results of magnetization measurements. The details of the mechanism of ferromagnetic ordering in the Co(2+) sublattice in La2CoIrO6 and the lack thereof in La2CoPtO6 are explained in terms of the orbital hybridization of the Co minority-spin t(2g) state and the Ir/Pt j(eff) = 1/2 state.
authors.affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul National University, Seoul 151-742, Korea. Department of Physics and Astronomy, Seoul National University (SNU), Seoul 151-742, Korea.
authors.forename: Min-Cheol
authors.initials: MC
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Sohn
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
authors.forename: K D
authors.initials: KD
authors.lastname: Lee
authors.forename: C J
authors.initials: CJ
authors.lastname: Won
authors.forename: N
authors.initials: N
authors.lastname: Hur
authors.forename: J-Y
authors.initials: JY
authors.lastname: Kim
authors.forename: Deok-Yong
authors.initials: DY
authors.lastname: Cho
authors.forename: T W
authors.initials: TW
authors.lastname: Noh