title: Strong coupling between 4f valence instability and 3d ferromagnetism in Yb(x)Fe4Sb12 studied by resonant x-ray emission spectroscopy.
abstract: We have investigated the temperature and pressure dependency of the electronic structure of Yb-filled skutterudites, YbFe(4)Sb(12) and Yb(0.88)Fe(4)Sb(12), using x-ray absorption and emission spectroscopies. An anomalous increase of the Yb valence, which is beyond the conventional Anderson model picture, is found to coincide with the onset of the ferromagnetic order in the x=0.88 sample below 20 K. In contrast, the nearly stoichiometric YbFe(4)Sb(12) is paramagnetic down to 2 K and the Yb valence is independent of temperature. This evidences a close interplay between the magnetic instability of the Fe 3d electrons and valence instability of the Yb 4f electrons. Under pressure, a sudden increase in the valence is found to occur around 13 GPa for YbFe(4)Sb(12) and 17 GPa for Yb(0.88)YbFe(4)Sb(12).
authors: Harima Institute, The Institute of Physical and Chemical Research (RIKEN), Sayo, Hyogo 679-5148, Japan.
authors: Hitoshi
authors: H
authors: Yamaoka
authors: Ignace
authors: I
authors: Jarrige
authors: Naohito
authors: N
authors: Tsujii
authors: Jung-Fu
authors: JF
authors: Lin
authors: Tsuyoshi
authors: T
authors: Ikeno
authors: Yosikazu
authors: Y
authors: Isikawa
authors: Katsuhiko
authors: K
authors: Nishimura
authors: Ryuji
authors: R
authors: Higashinaka
authors: Hideyuki
authors: H
authors: Sato
authors: Nozomu
authors: N
authors: Hiraoka
authors: Hirofumi
authors: H
authors: Ishii
authors: Ku-Ding
authors: KD
authors: Tsuei