左右対称な物質に現れた「電子の利き手」 ―ウラン化合物で新しい電子秩序を発見―

2026-07-28 日本原子力研究開発機構,東北大学

ウラン化合物で見つかった新しい電子の秩序状態(イメージ)。ウラン原子周りの電子の広がりが方向性を持ち、その配列が全体として「カイラリティ」を持つ（カイラル反強四極子秩序）

＜関連情報＞

• https://www.jaea.go.jp/02/press2026/p26072801/
• https://journals.aps.org/prl/abstract/10.1103/1vjx-4jfv

URhSnにおける自発的電子カイラル秩序のNMRによる解明 NMR Evidence for Spontaneous Electronic Chiral Order in URhSn

Y. Tokunaga, T. Ishitobi, H. Sakai, S. Kambe, H. Harima, A. Nakamura, A. Maurya, D. Li, Y. Homma et al.
Physical Review Letters  Published: 20 July, 2026
DOI: https://doi.org/10.1103/1vjx-4jfv

Abstract

URhSn exhibits successive phase transitions at T_O=54  K and T_C =16  K. While the transition at T_C is known to be ferromagnetic, the nature of the intermediate phase between T_O and T_C has remained elusive. Here, we report ¹¹⁷Sn nuclear magnetic resonance (NMR) measurements on high-quality single crystals of URhSn, which reveal NMR line splittings indicative of symmetry breaking in the intermediate phase. The field-direction and site dependences of these splittings are consistent with antiferroquadrupolar ordering characterized by the space group ⁢321 (No. 150). This finding confirms the emergence of a novel form of chiral order driven by electronic degrees of freedom, without an underlying chiral crystal structure in URhSn.