ウラン半導体に磁気の「強弱の波」を発見 ―層状磁性体の磁気制御に向けた新たな手がかり―

2026-08-21 日本原子力研究開発機構

＜関連情報＞

• https://www.jaea.go.jp/02/press2026/p26082102/
• https://journals.aps.org/prb/abstract/10.1103/jls4-6s89

5f電子系ファンデルワールス半導体磁性体α-UTe3における振幅変調型の非整合反強磁性 Incommensurate antiferromagnetism with amplitude modulation in the semiconducting 5⁢ van der Waals magnet −UTe3

Hironori Sakai, Chihiro Tabata, Koji Kaneko, Yoshifumi Tokiwa, Takafumi Kitazawa, Shinsaku Kambe, Yo Tokunaga, and Yoshinori Haga
Physical Review B  Published: 7 August, 2026
DOI: https://doi.org/10.1103/jls4-6s89

Abstract

α−UTe3, a van der Waals (vdW) actinide compound with a monoclinic ZrSe₃-type structure, is a narrow-gap semiconductor with 5⁢ƒ moments. ¹²⁵Te NMR reveals strongly anisotropic, layer-confined spin fluctuations below ∼20K, with the -axis component enhanced, and a signal wipeout at the antiferromagnetic (AFM) transition T_N=5K. Single-crystal neutron diffraction finds q≈(0.17,0.5,0) and a longitudinal sinusoidal modulation of α-axis moments (amplitude ≈0.8μ⁢_B) with AFM stacking along . A crystal electric field singlet-singlet induced-moment framework accounts for the easy-axis anisotropy, the small heat-capacity anomaly at T_N, the reduced ordered moment, and the exchange-driven selection of q in this localized 5ƒ vdW magnet, establishing a constrained exchange geometry stabilizing this in-plane incommensurate state.