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arXiv · 2606.22896

Coherent seeding and control of dynamical ferroelectricity by phonon anharmonicity

Junhan Huang·Yongkang Ju·Xinbo Wang·Li Yue·Hao Wang·Qiaomei Liu·Tianchen Hu·Yuchen Cui·Liyu Shi·Shangfei Wu·Sijie Zhang·Dong Wu·Peizhe Tang·Tao Dong·Nan-Lin Wang
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Abstract

Optical control of quantum materials has progressed along two separate directions: creating non-equilibrium states inaccessible at equilibrium, and coherently controlling ultrafast dynamics with multi-pulse protocols. Ferroelectricity is especially attractive in this context because its order parameter, macroscopic polarization, directly links inversion-symmetry breaking to functional response. Yet light-induced ferroelectricity has so far been confined to quantum paraelectrics near the ferroelectric instability, where critical fluctuations obscure the formation of a homogeneous ferroelectric state and complicate its deterministic coherent control. Unifying these capabilities -- preparing a symmetry-broken state and then coherently steering its functionality -- remains a central challenge. Here we show that intense terahertz excitation of a soft phonon mode induces a ferroelectric state in centrosymmetric PbTe, a thermoelectric material with strong lattice anharmonicity but no ferroelectric transition at finite temperature. The light-induced symmetry-broken state can be realized up to about 100 K, without relying on local dipolar fluctuations. Experiment and theory together reveal that terahertz-driven anharmonic coupling between degenerate transverse optical phonons underlies this ferroelectric induction. Furthermore, we demonstrate coherent amplification and suppression of the induced polarization via a double-pulse-excitation protocol. These results establish terahertz-driven anharmonic mode coupling as a general strategy for controlling mode-mediated functionalities in quantum materials, opening a route to ultrafast information processing.

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Junhan Huang, Yongkang Ju, Xinbo Wang, Li Yue, Hao Wang, Qiaomei Liu, Tianchen Hu, Yuchen Cui, Liyu Shi, Shangfei Wu, Sijie Zhang, Dong Wu, Peizhe Tang, Tao Dong, Nan-Lin Wang. 2026-06-22. Coherent seeding and control of dynamical ferroelectricity by phonon anharmonicity. https://arxiv.org/abs/2606.22896

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