Magnetism in La1−xSrxCoO3 as a function of doping is investigated with X-ray absorption spectroscopy and X-ray magnetic circular dichroism 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 EF 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 t2g character for the undistorted pseudocubic structure. Supercell calculations show stronger magnetism on oxygen atoms having more Sr neighbors.
@article{arxiv.1210.3396,
title = {Evolution of magnetic oxygen states in Sr-doped LaCoO$_3$},
author = {S. Medling and Y. Lee and H. Zhang and J. F. Mitchell and J. W. Freeland and B. N. Harmon and F. Bridges},
journal= {arXiv preprint arXiv:1210.3396},
year = {2012}
}