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arXiv · 2502.16442

Long-Range Spin-Orbit-Coupled Magnetoelectricity in Type-II Multiferroic NiI$_2$

Weiyi Pan·Zefeng Chen·Dezhao Wu·Weiqin Zhu·Zhiming Xu·Lianchuang Li·Junsheng Feng·Bing-Lin Gu·Wenhui Duan·Changsong Xu
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Abstract

Type-II multiferroics, where spin order induces ferroelectricity, exhibit strong magnetoelectric coupling. However, for the typical 2D type-II multiferroic NiI$_2$, the underlying magnetoelectric mechanism remains unclear. Here, applying generalized spin-current model, together with first-principles calculations and a tight-binding approach, we build a comprehensive magnetoelectric model for spin-induced polarization. Such model reveals that the spin-orbit coupling extends its influence to the third-nearest neighbors, whose contribution to polarization rivals that of the first-nearest neighbors. By analyzing the orbital-resolved contributions to polarization, our tight-binding model reveals that the long-range magnetoelectric coupling is enabled by the strong $e_g$-$p$ hopping of NiI$_2$. Monte Carlo simulations further predict a Bloch-type magnetic skyrmion lattice at moderate magnetic fields, accompanied by polar vortex arrays. These findings can guide the discovery and design of strongly magnetoelectric multiferroics.

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Weiyi Pan, Zefeng Chen, Dezhao Wu, Weiqin Zhu, Zhiming Xu, Lianchuang Li, Junsheng Feng, Bing-Lin Gu, Wenhui Duan, Changsong Xu. 2025-02-23. Long-Range Spin-Orbit-Coupled Magnetoelectricity in Type-II Multiferroic NiI$_2$. https://arxiv.org/abs/2502.16442

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