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arXiv · 2505.09958

Terahertz-field activation of polar skyrons

Huaiyu Wang·Vladimir Stoica·Cheng Dai·Marek Paściak·Sujit Das·Tiannan Yang·Mauro A. P. Gonçalves·Jiri Kulda·Margaret R. McCarter·Anudeep Mangu·Yue Cao·Hari Padma·Utkarsh Saha·Diling Zhu·Takahiro Sato·Sanghoon Song·Mathias Hoffmann·Patrick Kramer·Silke Nelson·Yanwen Sun·Quynh Nguyen·Zhan Zhang·Ramamoorthy Ramesh·Lane Martin·Aaron M. Lindenberg·Long-Qing Chen·John W. Freeland·Jirka Hlinka·Venkatraman Gopalan·Haidan Wen
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Abstract

Unraveling collective modes arising from coupled degrees of freedom is crucial for understanding complex interactions in solids and developing new functionalities. Unique collective behaviors emerge when two degrees of freedom, ordered on distinct length scales, interact. Polar skyrmions, three-dimensional electric polarization textures in ferroelectric superlattices, disrupt the lattice continuity at the nanometer scale with nontrivial topology, leading to previously unexplored collective modes. Here, using terahertz-field excitation and femtosecond x-ray diffraction, we discovered subterahertz collective modes, dubbed 'skyrons', which appear as swirling patterns of atomic displacements functioning as atomic-scale gearsets. Momentum-resolved time-domain measurements of diffuse scattering revealed an avoided crossing in the dispersion relation of skyrons. We further demonstrated that the amplitude and dispersion of skyrons can be controlled by sample temperature and electric-field bias. Atomistic simulations and dynamical phase-field modeling provided microscopic insights into the three-dimensional crystallographic and polarization dynamics. The discovery of skyrons and their coupling with terahertz fields opens avenues for ultrafast control of topological polar structures.

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Huaiyu Wang, Vladimir Stoica, Cheng Dai, Marek Paściak, Sujit Das, Tiannan Yang, Mauro A. P. Gonçalves, Jiri Kulda, Margaret R. McCarter, Anudeep Mangu, Yue Cao, Hari Padma, Utkarsh Saha, Diling Zhu, Takahiro Sato, Sanghoon Song, Mathias Hoffmann, Patrick Kramer, Silke Nelson, Yanwen Sun, Quynh Nguyen, Zhan Zhang, Ramamoorthy Ramesh, Lane Martin, Aaron M. Lindenberg, Long-Qing Chen, John W. Freeland, Jirka Hlinka, Venkatraman Gopalan, Haidan Wen. 2025-05-15. Terahertz-field activation of polar skyrons. https://doi.org/10.1038/s41467-025-64033-6

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