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arXiv · 2607.09003

Magnetic devil's staircase in UAgBi$_{2}$

G. S. Freitas·K. Kirchner·C. Girod·D. R. Yahne·W. Simeth·C. S. T. Kengle·F. B. Carneiro·P. G. Pagliuso·J. D. Thompson·M. Janoschek·O. Zaharko·S. M. Thomas·P. F. S. Rosa
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Abstract

Materials characterized by competing interactions often exhibit a large number of nearly degenerate periodic states. Here we show that layered UAgBi$_2$ hosts a cascade of field- and temperature-induced magnetic transitions. Based on specific heat, thermal expansion, and neutron diffraction, we construct a phase diagram that reveals at least seven nearly degenerate magnetic states in UAgBi$_2$. The observed multi-step magnetization process can be understood by square-wave structures with distinct propagation vectors $\mathbf{k}$=(0, 0, \textit{k}) in the presence of strong easy-axis anisotropy that confines the moments along the \textit{c} axis. Our findings are consistent with a magnetic devil's staircase described by the axial next-nearest neighbor Ising (ANNNI) model and place UAgBi$_2$ as a rare realization of the devil's staircase in a 5\textit{f}-electron system.

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G. S. Freitas, K. Kirchner, C. Girod, D. R. Yahne, W. Simeth, C. S. T. Kengle, F. B. Carneiro, P. G. Pagliuso, J. D. Thompson, M. Janoschek, O. Zaharko, S. M. Thomas, P. F. S. Rosa. 2026-07-10. Magnetic devil's staircase in UAgBi$_{2}$. https://arxiv.org/abs/2607.09003

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