Medling, ScottLee, Y.Zheng, H.Mitchell, J.F.Freeland, J.W.Harmon, B.N.Bridges, F.2015-12-100031-9007http://hdl.handle.net/1885/65019Magnetism in La 1-xSr xCoO 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.Keywords: Ferromagnetic clusters; First principles electronic structure; Magnetic state; Nonmagnetic groundstates; Nonmagnetic insulating matrix; O K-edges; Oxygen atom; Pseudocubic structure; Rhombohedral distortion; Sr doping; Supercell calculations; Cobalt compo201210.1103/PhysRevLett.109.1572042016-02-24