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arXiv · 2505.11860

Robust superzone gap opening in incommensurate antiferromagnetic semimetal EuAg$_4$Sb$_2$ under in-plane magnetic field

J. Green·Arpit Arora·Madalynn Marshall·Wanfei Shan·Péter Udvarhelyi·Zachary Morgan·Prineha Narang·Huibo Cao·Ni Ni
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Abstract

The interplay between magnetism and charge transport in semimetals has emerged as a fertile ground for discovering novel electronic phenomena. A notable example is the recent discovery of electronic commensuration arising from a spin moir\'e superlattice (SMS), realized as double-q spin modulation in the antiferromagnetic semimetal EuAg$_4$Sb$_2$. Here, we investigate the in-plane magnetic-field tunability of the SMS using neutron scattering, magnetic and transport measurements. We reveal an incommensurate noncollinear cycloidal magnetic ground state. Temperature-field phase diagrams constructed with field tilting uncover multiple spin-reoriented phases, suggesting the critical role of in-plane field components in driving magnetic transitions. Despite substantial spin reorientation of the double-q phase, we observe a persistent gap opening, evidenced by strong suppression in both Hall and longitudinal conductivities. Model calculations attribute this robustness to the stability of SMS under tilting fields. Our results establish EuAg$_4$Sb$_2$ as a tunable platform for exploring spin-texture-driven superzone gap opening in electronic states.

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J. Green, Arpit Arora, Madalynn Marshall, Wanfei Shan, Péter Udvarhelyi, Zachary Morgan, Prineha Narang, Huibo Cao, Ni Ni. 2025-05-17. Robust superzone gap opening in incommensurate antiferromagnetic semimetal EuAg$_4$Sb$_2$ under in-plane magnetic field. https://arxiv.org/abs/2505.11860

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