Imaging of 180∘ ferroelectric domain walls in uniaxial ferroelectrics by confocal Raman spectroscopy: Unraveling the contrast mechanism
| Autor: | Simone Sanna, Wolf Gero Schmidt, Christof Eigner, Gerhard Berth, Michael Rüsing, Julian Brockmeier, K. J. Spychala, Sergej Neufeld, P. Mackwitz, Christine Silberhorn, Artur Zrenner |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Physics and Astronomy (miscellaneous) Condensed matter physics Scattering Phonon Relaxation (NMR) 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Ferroelectricity Domain (software engineering) Domain wall (string theory) symbols.namesake 0103 physical sciences Dispersion (optics) symbols General Materials Science 0210 nano-technology Raman spectroscopy |
| Zdroj: | Physical Review Materials. 2 |
| ISSN: | 2475-9953 |
| Popis: | In recent years, Raman spectroscopy has been used to visualize and analyze ferroelectric domain structures. The technique makes use of the fact that the intensity or frequency of certain phonons is strongly influenced by the presence of domain walls. Although the method is used frequently, the underlying mechanism responsible for the changes in the spectra is not fully understood. This inhibits deeper analysis of domain structures based on this method. Two different models have been proposed. However, neither model completely explains all observations. In this work, we have systematically investigated domain walls in different scattering geometries with Raman spectroscopy in the common ferroelectric materials used in integrated optics, i.e., KTiOPO4, LiNbO3, and LiTaO3. Based on the two models, we can demonstrate that the observed contrast for domain walls is in fact based on two different effects. We can identify on the one hand microscopic changes at the domain wall, e.g., strain and electric fields, and on the other hand a macroscopic change of selection rules at the domain wall. While the macroscopic relaxation of selection rules can be explained by the directional dispersion of the phonons in agreement with previous propositions, the microscopic changes can be explained qualitatively in terms of a simplified atomistic model. |
| Databáze: | OpenAIRE |
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