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Unconventional spectral changes across the metal-insulator transition in CeTiO 3 + δ

1997; American Physical Society; Volume: 56; Issue: 19 Linguagem: Inglês

10.1103/physrevb.56.12050

1095-3795

O. Akaki, A. Chainani, T. Yokoya, H. Fujisawa, T. Takahashi, M. Sohma,

Electronic and Structural Properties of Oxides

We study the change in the electronic structure of ${\mathrm{CeTiO}}_{3+\mathrm{\ensuremath{\delta}}}$ across the \ensuremath{\delta}-controlled metal-insulator (M-I) transition. X-ray-absorption spectroscopy shows the formation of hole states with substantial $O$ $2p$ character as a function of \ensuremath{\delta}. Ultraviolet photoemission spectroscopy confirms the gap $(<100\mathrm{meV})$ closure across the M-I transition due to the doped hole states. The results show that a Mott-Hubbard system can have a charge-transfer character due to the strong hybridization, indicating a very mixed character ground state.