Electronic structure of CuSi (Yb, Y) studied by soft X-ray angle-resolved photoemission spectroscopy

Yasui, Akira; Fujimori, Shinichi   ; Kawasaki, Ikuto  ; Okane, Tetsuo  ; Takeda, Yukiharu   ; Saito, Yuji  ; Yamagami, Hiroshi; Sekiyama, Akira*; Settai, Rikio*; Matsuda, Tatsuma; Haga, Yoshinori   ; Onuki, Yoshichika*

In recent years, electronic structure of YbCuSi, which is a classical example of Yb-based valence fluctuation compounds, has been studied by various experimental methods such as quantum oscillation measurement and angle-integrated photoemission spectroscopy (AIPES). However, these results are inconsistent each other. In fact, the band structure calculation which well describes the results of the quantum oscillation measurement cannot explain the AIPES spectrum. In the present study, we have performed the soft X-ray angle-resolved photoemission spectroscopy (ARPES) for YbCuSi to understand the valence band structure and the Fermi surface (FS) in a unified way. We will discuss its electronic structure by comparing the ARPES spectra with those of YCuSi, which can be regarded as a reference compound for YbCuSi in the Yb trivalent state.