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arXiv · 2604.24951

Crystal-Field Symmetry Constraints in Layered Honeycomb ErBr$_3$

Biaoyan Hu·Mingyuan Hu·Franz Demmel·Andrey A. Podlesnyak·Jiaqing He·Liusuo Wu
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Abstract

Crystal-field symmetry restricts the ground-state Kramers doublet of ErBr$_3$ to one of two classes. We show that the compressed octahedral environment selects the class with $\langle \psi_\pm | J^{\pm} | \psi_\mp \rangle = 0$, suppressing the lowest-order $J^{\pm}$-mediated exchange. Thermodynamic measurements reveal two zero-field anomalies at 0.375 and 0.200~K. Under an in-plane magnetic field, the thermodynamic response separates into a phase boundary and a broader crossover line. Inelastic neutron scattering measurements at 2 K reveal no well-defined low-energy dispersive magnetic modes. These results connect the ground-state symmetry with the field-dependent thermodynamic response of ErBr$_3$, providing a microscopic starting point for understanding its low-energy magnetic behavior.

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Biaoyan Hu, Mingyuan Hu, Franz Demmel, Andrey A. Podlesnyak, Jiaqing He, Liusuo Wu. 2026-04-27. Crystal-Field Symmetry Constraints in Layered Honeycomb ErBr$_3$. https://doi.org/10.1103/7v1d-gc1p

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