The electronic structure of KTaO3: a combined x-ray spectroscopic investigation

Abstract

The electronic structure of potassium tantalate (KTaO3) is studied by various spectroscopic techniques, namely x-ray photoelectron spectroscopy (XPS), x-ray emission spectroscopy (XES), and x-ray absorption spectroscopy (XAS). The experiments are compared with theoretical band structure calculations. Excellent agreement between theory and experiment is achieved. XPS and XES reveal that the valence band is dominated by strongly hybridized Ta 5d and O 2p states. Furthermore, we find that the Ta N-III resonant inelastic x-ray spectroscopy (RIXS) spectra consist of three distinct features. For excitation energies close to the Ta 4p absorption threshold an elastic recombination peak and a resonant Raman-like loss feature are present in addition to nonresonant-like x-ray emission. In comparison with band structure calculations we are able to assign the loss feature to charge transfer excitations between occupied Ta 5d and O 2p states and unoccupied Ta 5d states.