title: Evolution of magnetic oxygen states in Sr-doped LaCoO3.
abstract: Magnetism in La(1-x)Sr(x)CoO(3) as a function of doping is investigated with x-ray absorption spectroscopy and x-ray magnetic circular dicrhoism at the O K edge, and corresponding first principles electronic structure calculations. For small x, the spectra are consistent with the formation of ferromagnetic clusters occurring within a nonmagnetic insulating matrix. Sr-induced, magnetic O-hole states form just above E(F) and grow with increasing Sr doping. Density functional calculations for x=0 yield a nonmagnetic ground state with the observed rhombohedral distortion and indicates that doping introduces holes at the Fermi level in magnetic states with significant O 2p and Co t(2g) character for the undistorted pseudocubic structure. Supercell calculations show stronger magnetism on oxygen atoms having more Sr neighbors.
authors.affiliation: Department of Physics, University of California, Santa Cruz, California 95064, USA.
authors.forename: S
authors.initials: S
authors.lastname: Medling
authors.forename: Y
authors.initials: Y
authors.lastname: Lee
authors.forename: H
authors.initials: H
authors.lastname: Zheng
authors.forename: J F
authors.initials: JF
authors.lastname: Mitchell
authors.forename: J W
authors.initials: JW
authors.lastname: Freeland
authors.forename: B N
authors.initials: BN
authors.lastname: Harmon
authors.forename: F
authors.initials: F
authors.lastname: Bridges