Terahertz-field activation of polar skyrons
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.
Keywords
Cite
@article{arxiv.2505.09958,
title = {Terahertz-field activation of polar skyrons},
author = {Huaiyu Wang and Vladimir Stoica and Cheng Dai and Marek Paściak and Sujit Das and Tiannan Yang and Mauro A. P. Gonçalves and Jiri Kulda and Margaret R. McCarter and Anudeep Mangu and Yue Cao and Hari Padma and Utkarsh Saha and Diling Zhu and Takahiro Sato and Sanghoon Song and Mathias Hoffmann and Patrick Kramer and Silke Nelson and Yanwen Sun and Quynh Nguyen and Zhan Zhang and Ramamoorthy Ramesh and Lane Martin and Aaron M. Lindenberg and Long-Qing Chen and John W. Freeland and Jirka Hlinka and Venkatraman Gopalan and Haidan Wen},
journal= {arXiv preprint arXiv:2505.09958},
year = {2025}
}