Mn K-edge X-ray absorption spectroscopy (XAS) studies of La_(1-x)Sr_xMnO_3

摘要

Systematic Mn K-edge x-ray absorption spectroscopy (XAS) measurements on samples of La_(1-x)Sr_xMnO_3, which are precursors to colossal magnetoresistive (CMR) materials, are reported. Detailed results on the edge or chemical shift as a function of Sr concentration (hole doping) and sample preparation (air vs oxygen annealed), are discussed. For comparison, a systematic XANES Study of the Mn K-edge energy shift, denoting valence change in Mn, has been made in standard managese oxide systems. Contrary to expectations, the variation in near-edge energies for Mn inLa_(0.725)Sr_(0.275)MnO_3 were small when compared to the difference between that for manganese oxide standards of nominal valence of +3 and +4 (Mn_2O_3 and MnO_2).