2026-05-20 東京大学,理化学研究所,高輝度光科学研究センター,科学技術振興機構
結晶中に潜む四量体型の金属分子
＜関連情報＞
- https://www.k.u-tokyo.ac.jp/information/category/press/0029879.html
- https://journals.aps.org/prl/abstract/10.1103/qq1h-lgbc
非磁性パイロクロアニオブ酸塩における線状四量体形成 Linear Tetramer Formation in Nonmagnetic Pyrochlore Niobate
Shota Nishida, Shunsuke Kitou, Shingo Toyoda, Yuiga Nakamura, Yusuke Tokunaga, and Taka-hisa Arima
Physical Review Letters Published: 19 May, 2026
DOI: https://doi.org/10.1103/qq1h-lgbc
Abstract
We investigate displacive short-range order in pyrochlore Y2Nb2O7, which exhibits a nonmagnetic insulating state despite the presence of formally tetravalent Nb4+ (S=1/2) ions on the pyrochlore network. Synchrotron x-ray diffraction on a single crystal reveals a characteristic x-ray diffuse scattering (XDS) pattern primarily around q={0.5,0.5,2}. Reverse Monte Carlo (RMC) simulations uncover local Nb displacements along the ⟨111⟩ axes, leading to the formation of linear Nb4 tetramers. Our findings highlight a crucial role of molecular orbital degrees of freedom in stabilizing the nonmagnetic insulating state. This study demonstrates that RMC analysis of XDS provides a powerful approach for elucidating short-range correlations and the underlying mechanisms governing the physical properties of crystalline materials.
