Regensburg 2019 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 10: Ferroics - Domains and Domain Walls
KFM 10.2: Vortrag
Dienstag, 2. April 2019, 09:45–10:00, H47
External-field induced domain wall dynamics in LiNbO3 and BaTiO3 single crystals imaged by in-situ 3D Cherenkov second harmonic generation microscopy — •Benjamin Kirbus, Christian Godau, Lukas Wehmeier, Elke Beyreuther, Alexander Haußmann, and Lukas Eng — Institut für Angewandte Physik, TU Dresden, Nöthnitzer Str. 61, 01187 Dresden
Cherenkov second harmonic generation (CSHG) microscopy poses a powerful new tool [1,2] for the 3D imaging of ferroelectric domain walls (DWs). Investigating LiNbO3 crystals, 10-nm-thick Cr electrodes were deposited onto the samples. The z+ side was grounded and a ramped potential applied to the z− side. When increasing the field up to +4.0 kV/mm, laser-poled hexagonal domains were observed in real-time and in-situ to collapse into inclined, coned structures, forming highly conductive head-to-head DWs [3]. Consequently, the domain-wall current (DWC) increased by over 4 orders of magnitude, reaching values of >1 µA. A reversed poling field down to -3.6 kV/mm led to reversible and irreversible domain-shape recovery. Expansion of spike domains increased the DWC up to >1 mA.
The crystal symmetry of BaTiO3 allows much more complex domain patterns [4], such as 90∘ domain walls. Their kinetics upon phase transition will also be discussed using 3D CSHG imagery.
[1] L. Wehmeier et al. Phys. Status Solidi RRL 11, 1700267 (2017).
[2] T. Kämpfe et al. Phys. Rev. B 8, 035314 (2014).
[3] C. Godau et al. ACS Nano 11, 4816 (2017).
[4] J. Döring et al. J. Appl. Phys. 120, 084103 (2016).