Probing the Ba 5d states in BaTiO and BaSO; A Resonant X-ray emission study at the Ba-L edge

Yoshii, Kenji; Jarrige, I.; Matsumura, Daiju; Nishihata, Yasuo; Suzuki, Chikashi; Ito, Yoshiaki*; Mukoyama, Takeshi*; Tochio, Tatsunori*; Shinotsuka, Hiroshi*; Fukushima, Sei*

no journal, , 

We have directly probed the Ba 5d states in the ferroelectric BaTiO by resonant X-ray emission spectroscopy (RXES) and X-ray absorption spectroscopy in the partial fluorescence mode (PFY-XAS) at the Ba-L edge. The results are compared with those of the non-ferroelectric barium sulfate BaSO. While the RXES spectra point to a localized character for the Ba 5d states in both compounds, the main peak of the PFY-XAS spectrum is found to be significantly broader for BaTiO than for BaSO. On the basis of band structure calculations, this broadening is ascribed to strong hybridization between the unoccupied Ba 5d and O 2p states in the ferroelectric phase. This suggests that the hybridization between the conduction states of the Ba and O ions, and not only Ti and O, plays some roles in the occurrence of ferroelectricity in BaTiO.