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arXiv · 2607.14029

Unified Terahertz Framework for Magnetic and Lattice Responses Reveals an Elusive Ordering Transition in Gd$_2$Ru$_2$O$_7$

Nicolas M. Kawahala·Rafael L. Sabainsk·Esteban Marulanda·Rafael S. Freitas·Felix G. G. Hernandez
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Abstract

Magnetic order in materials combining localized rare-earth moments with itinerant transition-metal sublattices generates internal fields whose lattice imprint is rarely accessed directly. In Gd pyrochlore ruthenate, we find that a single terahertz spectrum resolves an exchange-split Gd$^{3+}$ mode and an optical phonon. Their coupled evolution quantifies the internal field, oriented as predicted for cluster-multipolar order, and reveals a Gd-ordering transition elusive to bulk thermodynamic probes, establishing a unified framework for accessing magnetic and lattice responses in correlated quantum materials.

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Nicolas M. Kawahala, Rafael L. Sabainsk, Esteban Marulanda, Rafael S. Freitas, Felix G. G. Hernandez. 2026-07-15. Unified Terahertz Framework for Magnetic and Lattice Responses Reveals an Elusive Ordering Transition in Gd$_2$Ru$_2$O$_7$. https://arxiv.org/abs/2607.14029

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