ELECTRONIC-STRUCTURE OF SR2RUO4 - X-RAY-FLUORESCENCE EMISSION STUDY

The results of measurements of O 1s total x-ray-fluorescence yield and Ru N-2,N-3 and O K-alpha x-ray fluorescence emission spectra of Sr2Ru O4 and Sr2Ru4.25 are presented. An excitation energy dependence of the O K-alpha x-ray emission spectra (XES) was observed in both compounds . The energy dependence of the spectra is attributed to the excitation of inequivalent O(1) in-plant and O(2) apical oxygens. The O(1) 2p an d O(2) 2p density of states distribution in the valence band of Sr2RuO 4 was found to be different in accordance with the results of band-str ucture calculations. O(1) 2p states are found to be mixed with Ru 4d(t (2g) states providing the formation of pi bonds. While the O K-alpha X ES spectra are in fair agreement with hand structure calculations, the theoretical two-peak distribution of Ru N-2,N-3 XES is found to be di fferent with respect to the intensity ratios and widths of the peaks o f Ru N-2,N-3 XES. These differences an attributed to a decrease of int ensity of radiative 4d --> 4p transitions in the vicinity of the Fermi level (where the localization of Ru 4d states is higher than at the b ottom of the valence band) due to a strong Kuster-Kronig transition.