O 1s X-ray absorption spectra and band structure calculations of Ca1-xSrxRuO3

We studied the electronic structure of the Ca1-xSrxRuO3 series using O 1s X-ray absorption spectroscopy (XAS). The XAS spectra were analyzed in terms of the O 2p unoccupied electronic states calculated using the LMTO method. The spectra reflect, through the covalent mixing, the different unoccupied electronic states in the conduction band. The first peak in the XAS spectra, just above the threshold, corresponds to O 2p character mixed in the Ru t2g band. This feature is directly related to the Ru t2g DOS at the Fermi level and does not change much across the series. The features related to the Ru eg and Ca 3d (Sr 4d) bands at higher energies present larger changes across the series. In particular, the Ca 3d band appears at lower energies and exhibits a larger mixing with the O 2p states than the Sr 4d band. This effect might be related to the differences in the magnetic properties of the end members CaRuO3 and SrRuO3