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arXiv · 2510.08746

Crystal-Field--Driven Magnetoelectricity in the Triangular Quantum Magnet CeMgAl$_{11}$O$_{19}$

Sonu Kumar·Gaël Bastien·Maxim Savinov·Petr Proschek·Adam Eliáš·Karol Załęski·Małgorzata Śliwińska-Bartkowiak·Ross H. Colman·Stanislav Kamba
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Abstract

We report dielectric and magnetoelectric studies of single-crystalline \ce{CeMgAl11O19}, a Kramers triangular magnet embedded in a polarizable hexaaluminate lattice. In zero magnetic field, the permittivity $\varepsilon'(T)$ follows the Barrett law of a quantum paraelectric down to 25 K, below which a broad minimum develops near 3 K without evidence of static ferroelectric or magnetic order. Application of magnetic fields up to \SI{9}{\tesla} shifts this minimum to higher temperatures and broadens it, evidencing a tunable magnetoelectric response.The magnetoelectric coupling was characterized using results from magnetization measurements. The anomaly temperature $T^*$, extracted from the local minimum of $\varepsilon'(T)$, exhibits a linear dependence on the squared magnetization $M^2$, consistent with the biquadratic magnetoelectric coupling allowed in centrosymmetric systems. This magnetoelectric effect, mediated by spin-orbit-entangled Kramers doublets interacting with a frustrated antipolar liquid, establishes \ce{CeMgAl11O19} as a prototype for exploring quantum magnetoelectricity in frustrated systems.

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Sonu Kumar, Gaël Bastien, Maxim Savinov, Petr Proschek, Adam Eliáš, Karol Załęski, Małgorzata Śliwińska-Bartkowiak, Ross H. Colman, Stanislav Kamba. 2025-10-09. Crystal-Field--Driven Magnetoelectricity in the Triangular Quantum Magnet CeMgAl$_{11}$O$_{19}$. https://doi.org/10.1103/c3hd-pwby

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