Electronic structure of the hole-doped delafossite oxides CuCr 1-xMgxO2

T. Yokobori, M. Okawa, K. Konishi, R. Takei, K. Katayama, S. Oozono, T. Shinmura, T. Okuda, H. Wadati, E. Sakai, K. Ono, H. Kumigashira, M. Oshima, T. Sugiyama, E. Ikenaga, N. Hamada, T. Saitoh

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We report the detailed electronic structure of a hole-doped delafossite oxide CuCr1-xMgxO2 (0≤x≤0.03) studied by photoemission spectroscopy (PES), soft x-ray absorption spectroscopy (XAS), and band-structure calculations within the local-density approximation +U (LDA+U) scheme. Cr/Cu 3p-3d resonant PES reveals that the near-Fermi-level leading structure has primarily the Cr 3d character with a minor contribution from the Cu 3d through Cu 3d-O 2p-Cr 3d hybridization, having good agreement with the band-structure calculations. This indicates that a doped hole will have primarily the Cr 3d character. Cr 2p PES and L-edge XAS spectra exhibit typical Cr3+ features for all x, while the Cu L-edge XAS spectra exhibited a systematic change with x. This indicates now that the Cu valence is monovalent at x=0 and the doped hole should have Cu 3d character. Nevertheless, we surprisingly observed two types of charge-transfer satellites that should be attributed to Cu+ (3d10) and Cu2+ (3d9) like initial states in Cu 2p-3d resonant PES spectrum of at x=0, while Cu 2p PES spectra with no doubt shows the Cu+ character even for the lightly doped samples. We propose that these contradictory results can be understood by introducing not only the Cu 4s state, but also finite Cu 3d,4s-Cr 3d charge transfer via O 2p states in the ground-state electronic configuration.

Original languageEnglish
Article number195124
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number19
Publication statusPublished - 2013 May 17


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