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arXiv · 2508.13952

Piezomagnetism-driven magnetoelectric coupling in altermagnetic multiferroic K3Cr2F7

Ying Zhou·Hui-Min Zhang·Cheng-Ao Ji·Hongjun Xiang·Shuai Dong·James M. Rondinelli·Xue-Zeng Lu
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Abstract

Ferroelectric control of altermagnetism in momentum space has been studied widely, while the control of magnetism in real space of altermagnets are still rare. We present a design rule to identify multiferroicity in n=2 Ruddlesden-Popper halides. Our results show that a Jahn-Teller distortion can cooperate with oxygen octahedral rotations to break inversion symmetry, which we demonstrate in K3Cr2F7 and cation-ordered KAg2Cu2Cl7, and leads to a ferrielectric-to-ferroelectric phase transition in K3Cr2F7. Altermagnetic spin order in the ferrielectric phase of K3Cr2F7 transforms into a conventional antiferromagnetic order in the ferroelectric phase, at which strain/pressure engineered sizable changes of weak ferromagnetism can occur. Our study is not only conducive to realize strong magnetoelectric coupling in multiferroics, but also reveals more functionalities in altermagnetic materials.

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Ying Zhou, Hui-Min Zhang, Cheng-Ao Ji, Hongjun Xiang, Shuai Dong, James M. Rondinelli, Xue-Zeng Lu. 2025-08-19. Piezomagnetism-driven magnetoelectric coupling in altermagnetic multiferroic K3Cr2F7. https://arxiv.org/abs/2508.13952

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