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arXiv · 2510.10999

Collinear, incommensurate antiferromagnetism in van der Waals magnet alpha-UTe3

H. Sakai·C. Tabata·K. Kaneko·Y. Tokiwa·T. Kitazawa·S. Kambe·Y. Tokunaga·Y. Haga
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Abstract

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

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H. Sakai, C. Tabata, K. Kaneko, Y. Tokiwa, T. Kitazawa, S. Kambe, Y. Tokunaga, Y. Haga. 2025-10-13. Collinear, incommensurate antiferromagnetism in van der Waals magnet alpha-UTe3. https://doi.org/10.1103/jls4-6s89

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