X-Ray Photoemission Study of CuIr2S4:Ir3+Ir4+ Charge Ordering and the Effect of Light Illumination

K. Takubo, S. Hirata, J.-Y. Son, J. W. Quilty, T. Mizokawa, N. Matsumoto, and S. Nagata
Phys. Rev. Lett. 95, 246401 – Published 5 December 2005

Abstract

We have studied the electronic structure of the spinel-type compound CuIr2S4 using x-ray photoemission spectroscopy (XPS). CuIr2S4 undergoes a metal-insulator transition (MIT) at 226K. In going from the metallic to insulating states, the valence-band photoemission spectrum shows a gap opening at the Fermi level and a rigid-band shift of 0.15eV. In addition, the Ir 4f core-level spectrum is dramatically changed by the MIT. The Ir 4f line shape of the insulating state can be decomposed into two contributions, consistent with the charge disproportionation of Ir3+Ir4+=11. XPS measurements under laser irradiation indicate that the charge disproportionation of CuIr2S4 is very robust against photo-excitation in contrast to Cs2Au2Br6 which shows photo-induced valence transition.

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  • Received 17 March 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.246401

©2005 American Physical Society

Authors & Affiliations

K. Takubo1, S. Hirata1, J.-Y. Son2, J. W. Quilty2, T. Mizokawa1,2, N. Matsumoto3, and S. Nagata3

  • 1Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
  • 2PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama, Japan
  • 3Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido, 050-8585 Japan

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Vol. 95, Iss. 24 — 9 December 2005

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