Open AccessX-Ray Photoemission Study ofCuIr 2 S 4 : Ir 3 + − Ir
Author(s) -
Kou Takubo,
S. Hirata,
Jaeseok Son,
J. W. Quilty,
T. Mizokawa,
Nobuhiro Matsumoto,
Shoichi Nagata
Publication year - 2005
Publication title -
physical review letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.688
H-Index - 673
eISSN - 1079-7114
pISSN - 0031-9007
DOI - 10.1103/physrevlett.95.246401
Subject(s) - x ray photoelectron spectroscopy , disproportionation , photoemission spectroscopy , valence (chemistry) , materials science , fermi level , electronic structure , analytical chemistry (journal) , atomic physics , physics , condensed matter physics , chemistry , nuclear magnetic resonance , electron , nuclear physics , chromatography , biochemistry , quantum mechanics , catalysis
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 ~226 K. 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 ~0.15 eV. 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+=1:1. 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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