2025-10-08 東京大学,高輝度光科学研究センター,近畿大学,東北大学,理化学研究所,科学技術振興機構
スピン-軌道相互作用が強い4f電子の空間分布
＜関連情報＞
- https://www.k.u-tokyo.ac.jp/information/category/press/0027913.html
- https://www.k.u-tokyo.ac.jp/assets/電子の「自転」と「公転」がもつれ合う姿を可視化_WEB.pdf
- https://www.pnas.org/doi/10.1073/pnas.2500251122
結晶材料中のスピン軌道相互作用を持つ4f電子の可視化 Visualization of spin–orbit-entangled 4f electrons in crystalline materials
Shunsuke Kitou, Kentaro Ueda, Yuiga Nakamura, +4 , and Taka-hisa Arima
Proceedings of the National Academy of Sciences Published:October 6, 2025
DOI:https://doi.org/10.1073/pnas.2500251122
Significance
The anisotropic spatial distribution of lanthanide 4f electrons plays a pivotal role in governing key material properties, from magnetism to emergent quantum behaviors. However, their pronounced anisotropy and weak signals have posed significant challenges for direct visualization. This study introduces an innovative approach combining high-photon-energy X-ray diffraction and advanced valence electron density (VED) analysis, enabling the direct mapping of 4f electron distributions in pyrochlore oxides. This breakthrough not only sheds light on the fundamental nature of 4f electrons but also paves the way for exploring their role in a wide array of materials, opening avenues for material innovation.
Abstract
Lanthanide 4f electrons are strongly influenced by spin–orbit coupling, resulting in well-defined J multiplets, which are further split by the crystalline electric field in condensed matter. While the anisotropy of 4f electrons is closely linked to material properties, direct experimental observation of the 4f electron distribution in real space remains a significant challenge. Here, we present an approach for visualizing the anisotropic distribution of lanthanide 4f electrons in pyrochlore oxides by combining high-photon-energy X-ray diffraction and valence electron density (VED) analysis based on the core differential Fourier synthesis (CDFS) method. The observed VED distributions around the lanthanide site reveal the parameters of the ground-state wavefunction, which roughly agree with point-charge calculations for the trigonal crystal electric field under the LS coupling scheme. This CDFS-based VED observation method not only provides insights into the anisotropic nature of 4f electrons but also opens a pathway for studying the 4f states in a wide range of crystalline materials.
