In-gap state and effect of light illumination in CuIr2S 4 probed by photoemission spectroscopy

K. Takubo, T. Mizokawa, N. Matsumoto, S. Nagata

研究成果: Article査読

14 被引用数 (Scopus)


We have studied disorder-induced in-gap states and effect of light illumination in the insulating phase of spinel-type CuIr2S 4 using ultraviolet photoemission spectroscopy (UPS). The Ir 3+/Ir4+ charge-ordered gap appears below the metal-insulator transition temperature. However, in the insulating phase, in-gap spectral features with softgap are observed in UPS just below the Fermi level (EF), corresponding to the variable range hopping transport observed in resistivity. The spectral weight at EF is not increased by light illumination, indicating that the Ir4+-Ir4+ dimer is very robust, although the long-range octamer order would be destructed by the photoexcitation. Present results suggest that the Ir4+-Ir 4+ bipolaronic hopping and disorder effects are responsible for the conductivity of CuIr2S4.

ジャーナルPhysical Review B - Condensed Matter and Materials Physics
出版ステータスPublished - 2008 12 1

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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