Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 44: Focus Session: Surfaces and Interfaces of (Incipient) Ferroelectrics (joint session O/KFM)
O 44.5: Talk
Wednesday, September 7, 2022, 16:30–16:45, H3
Ferroelectric domain imaging in barium titanate using infrared-visible sum-frequency generation microscopy — •Dorothee Mader1, Daniel Lourens2, Maarten Kwaaitaal2, Richarda Niemann1, Sören Wasserroth1, Sandy Gewinner1, Marco De Pas1, Wieland Schöllkopf1, Martin Wolf1, Andrei Kirilyuk2, Sebastian F. Maehrlein1, and Alexander Paarmann1 — 1Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 2Radboud Universiteit, Nijmegen, The Netherlands
Phonons exhibit a mostly unexplored leverage on the mechanisms and dynamics of domain formation in ferroics. Here, a new method is employed combining resonant phonon excitation and ferroelectric domain imaging of barium titanate (BTO) using infrared-visible (IR-VIS) sum-frequency generation (SFG) microscopy [1]. BTO is a non-centrosymmetric perovskite oxide with a strong ferroelectric polarization in its tetragonal phase. Typically, BTO samples exhibit a multi-domain structure. In this contribution, SFG microscopy is shown to naturally provide domain contrast due to the polarization-induced local variation of the nonlinear susceptibility. Additionally, our spectral analysis of the SFG response reveals the domain-selective phonon resonances for all high-frequency phonons in the IR spectral range of 500-800 cm−1. By locally mapping phonon resonances in domains and domain walls, this approach may enable in-depth understanding of the underlying physics of domain formation and its dynamics. [1] R. Niemann et al., Appl. Phys. Lett. 120, 131102 (2022).