Impact of valence fluctuations on the electronic properties of RO1−xFxBiS2 (R=Ce and Pr)

We have investigated the electronic properties of BiS2-based superconductors by using x-ray photoemission spectroscopy (XPS). In going from x=0.3 to 0.5 in PrO1−xFxBiS2, the Pr 3d and Pr 4d peaks are shifted by ∼0.10±0.05 eV from the Fermi level, partially consistent with the electron doping. In PrO...

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Bibliographic Details
Published in:Physical review. B 2018-10, Vol.98 (14), p.144501
Main Authors: Dash, S, Morita, T, Kurokawa, K, Matsuzawa, Y, Saini, N L, Yamamoto, N, Kajitani, Joe, Higashinaka, R, Matsuda, T D, Aoki, Y, Mizokawa, T
Format: Article
Language:English
Subjects:
Binding energy
Cerium
Doping
Earth orbits
Electronic properties
Electrons
Occupations
Photoelectric emission
Praseodymium
Rare earth elements
Valence band
Variation
X ray photoelectron spectroscopy
X ray spectra
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Summary:We have investigated the electronic properties of BiS2-based superconductors by using x-ray photoemission spectroscopy (XPS). In going from x=0.3 to 0.5 in PrO1−xFxBiS2, the Pr 3d and Pr 4d peaks are shifted by ∼0.10±0.05 eV from the Fermi level, partially consistent with the electron doping. In PrO1−xFxBiS2, the Pr3+−Pr4+ mixed valence remains unchanged with the electron doping from x=0.3 to 0.5. In CeO1−xFxBiS2, the doped electrons for x=0.5 almost suppress the Ce3+−Ce4+ valence fluctuation. Although the core-level peaks are also shifted by ∼0.10±0.05 eV towards the higher-binding-energy side with the electron doping from x=0 to 0.5 in CeO1−xFxBiS2, the Bi 4f7/2 binding-energy shift is higher in the Pr system compared with the Ce system. The present results suggest that the doped electrons increase orbital occupations in the rare-earth 4f orbitals at the valence band and show valence fluctuations differently in the two systems.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.98.144501