Photoemission spectroscopy of the filled skutterudite compound YbFeSb

Okane, Tetsuo  ; Fujimori, Shinichi   ; Mamiya, Kazutoshi; Okamoto, Jun; Muramatsu, Yasuji; Fujimori, Atsushi; Nagamoto, Yasuyuki*; Koyanagi, Tsuyoshi*

The filled skutterudite compounds ( = alkaline earth, rare earth, actinide; = Fe, Ru, Os; = pnictogen: P, As, Sb) exhibit a variety of physical properties such as superconductivity, magnetic ordering, heavy-Fermion behavior, and metal-insulator transition. Among them, YbFeSb shows a heavy-Fermion or intermediate-valence behavior in the magnetic, electrical transport, and thermal properties, which might be associated with a valence instability of Yb atom. In this study, the electronic structure of YbFeSb have been investigated by the high-resolution photoemission spectroscopy, using He discharge lamp and synchrotron radiation as an excitation sources. The bulk and surface components of the Yb signal is clearly divided in the spectra. The relation of the energy position between them is anomalous compared to that of the conventional mixed-valent Yb compounds.