Observation of polarization density waves in SrTiO3

Gal Orenstein; Viktor Krapivin; Yijing Huang; Zhuquan Zhan; Gilberto de la Pena Munoz; Ryan A. Duncan; Quynh Nguyen; Jade Stanton; Samuel Teitelbaum; Hasan Yavas; Takahiro Sato; Matthias C. Hoffmann; Patrick Kramer; Jiahao Zhang; Andrea Cavalleri; Riccardo Comin; Mark P. M. Dean; Ankit S. Disa; Michael Forst; Steven L. Johnson; Matteo Mitrano; Andrew M. Rappe; David Reis; Diling Zhu; Keith A. Nelson; Mariano Trigo

arXiv · 2403.17203

Observation of polarization density waves in SrTiO3

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Abstract

The nature of the "failed" ferroelectric transition in SrTiO3 has been a long-standing puzzle in condensed matter physics. A compelling explanation is the competition between ferroelectricity and an instability with a mesoscopic modulation of the polarization. These polarization density waves, which should become especially strong near the quantum critical point, break local inversion symmetry and are difficult to probe with conventional x-ray scattering methods. Here we combine a femtosecond x-ray free electron laser (XFEL) with THz coherent control methods to probe inversion symmetry breaking at finite momenta and visualize the instability of the polarization on nanometer lengthscales in SrTiO3. We find polar-acoustic collective modes that are soft particularly at the tens of nanometer lengthscale. These precursor collective excitations provide evidence for the conjectured mesoscopic modulated phase in SrTiO3.

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Gal Orenstein, Viktor Krapivin, Yijing Huang, Zhuquan Zhan, Gilberto de la Pena Munoz, Ryan A. Duncan, Quynh Nguyen, Jade Stanton, Samuel Teitelbaum, Hasan Yavas, Takahiro Sato, Matthias C. Hoffmann, Patrick Kramer, Jiahao Zhang, Andrea Cavalleri, Riccardo Comin, Mark P. M. Dean, Ankit S. Disa, Michael Forst, Steven L. Johnson, Matteo Mitrano, Andrew M. Rappe, David Reis, Diling Zhu, Keith A. Nelson, Mariano Trigo. 2024-03-25. Observation of polarization density waves in SrTiO3. https://arxiv.org/abs/2403.17203

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