Yamaoka Hitoshi, Thunström Patrik, Tsujii Naohito, Katoh Kenichi, Yamamoto Yoshiya, Schwier Eike F, Shimada Kenya, Iwasawa Hideaki, Arita Masashi, Jarrige Ignace, Hiraoka Nozomu, Ishii Hirofumi, Tsuei Ku-Ding, Mizuki Jun'ichiro
RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
J Phys Condens Matter. 2017 Nov 29;29(47):475502. doi: 10.1088/1361-648X/aa8b98.
Electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d-4f resonance, resonant x-ray emission spectroscopy at the Yb L absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with large [Formula: see text] and small [Formula: see text] components. The magnitude of the Yb valence is evaluated to be YbPtGe [Formula: see text] YbPdGe [Formula: see text] YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.
