強相関電子系物質の相図におけるパラダイムシフト～半世紀使われてきたドニアック相図を超えて～

2026-01-21 理化学研究所

図1 CeRu₂Al₁₀の結晶構造、ARPES実験のセットアップ

＜関連情報＞

• https://www.riken.jp/press/2026/20260121_1/index.html
• https://journals.aps.org/prl/abstract/10.1103/hdcf-dycj

Ce⁢(Ru1−⁢Rh)2⁢Al10における移動型から局在型への重い電子磁性：ドニアック相図を超えた方向依存性相図 Itinerant to Localized Heavy Electron Magnetism in Ce⁢(Ru1−⁢Rh)2⁢Al10: A Direction-Dependent Phase Diagram beyond the Doniach Phase Diagram

Hitoshi Yamaoka, Hiroshi Tanida, Eike F. Schwier, Yoshiya Yamamoto, Shiv Kumar, Masashi Arita, Kenya Shimada, Fumisato Tajima, Renta Onodera et al.
Physical Review Letters  Published: 24 December, 2025
DOI: https://doi.org/10.1103/hdcf-dycj

Abstract

Electronic and crystal structures of Ce⁢(Ru_1−⁢Rh)₂⁢Al₁₀ have been studied using x-ray emission spectroscopy, photoelectron spectroscopy (PES), and x-ray diffraction. No structural phase transition was observed up to =0.1, while the x-ray absorption spectra showed a Ce valence transition between =0.03 and 0.05, accompanied by an increase in − hybridization strength, suggesting a Lifshitz transition. Angle-resolved PES conducted on the =0.1 sample revealed stronger hybridization along the axis compared to the other axes. Direction-dependent hybridization introduces complexity in applying conventional phase diagrams. For the first time, we propose a direction-dependent phase diagram for Ce⁢(Ru_1−⁢Rh)₂⁢Al₁₀, advancing beyond the traditional Doniach phase diagram.