Strong excitonic interactions in the oxygen K-edge of perovskite oxides.
Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO3, SrTiO3, and BaTiO3, together with reference oxides, MgO, CaO, SrO, BaO, and TiO2, were investigated using a first-principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds.
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
Kota
K
Tomita
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
Tomohiro
T
Miyata
Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.
Weine
W
Olovsson
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan. Electronic address: teru@iis.u-tokyo.ac.jp.
Teruyasu
T
Mizoguchi
Electron energy-loss near-edge structure; Exciton; First principles calculation; Oxygen K-edge; Perovskite oxides