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arXiv · 2507.20285

Type-II Antiferroelectricity

Yang Wang·Zhi-Ming Yu·Chaoxi Cui·Yilin Han·Tingli He·Weikang Wu·Run-Wu Zhang·Shengyuan A. Yang·Yugui Yao
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Abstract

Antiferroelectricity (AFE) is a fundamental concept in physics and materials science. Conventional AFEs have the picture of alternating local electric dipoles defined in real space. Here, we discover a new class of AFEs, termed type-II AFEs, which possess opposite polarizations defined in momentum space across a pair of symmetry decoupled subspaces. Unlike conventional AFEs, the order parameter of type-II AFEs is rigorously formulated through Berry-phase theory and can be quantitatively extracted from the electronic band structure. Focusing on a subclass of type-II AFEs that preserve spin-rotation symmetry, we establish the relevant symmetry constraints and identify all compatible spin point groups. Remarkably, we find that type-II AFE order intrinsically coexists with antiferromagnetism, revealing a robust form of magnetoelectric coupling. We construct an altermagnetic model and identify several concrete antiferromagnetic/altermagnetic materials, such as FeS, Cr2O3, MgMnO3, monolayer MoICl2 and bilayer CrI3, that exhibit this novel ordering. Furthermore, we uncover unique physical phenomena associated with type-II spin-AFE systems, including spin current generation upon AFE switching and localized spin polarization at boundaries and domain walls. Our findings reveal a previously hidden class of quantum materials with intertwined ferroic orders, offering exciting opportunities for both fundamental exploration and technological applications.

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Yang Wang, Zhi-Ming Yu, Chaoxi Cui, Yilin Han, Tingli He, Weikang Wu, Run-Wu Zhang, Shengyuan A. Yang, Yugui Yao. 2025-07-27. Type-II Antiferroelectricity. https://arxiv.org/abs/2507.20285

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