Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 28: Poster Session on Ferroic Domain Walls - Multiferroics (jointly with DF, KR, MA)
TT 28.7: Poster
Monday, March 16, 2015, 19:00–21:00, Poster C
Domain walls in lithium niobate investigated by Raman spectroscopy and density functional theory — •Sergej Neufeld1, Michael Rüsing2, Gerhard Berth2, Artur Zrenner2, Wolf Gero Schmidt1, and Simone Sanna1 — 1Lehrstuhl für Theoretische Physik, Universität Paderborn — 2Department Physik, Universität Paderborn
The intensity of the Raman signal associated to different phonon modes of LiNbO3 is strongly modified by the presence of ferroelectric domain boundaries [1]. The intensity modulation can be exploited to map domain structures, thus using Raman spectroscopy as a non-destructive imaging tool for the investigation of polarization-domains and domain walls [2]. Unfortunately, the origin of the modifications in the Raman signal is currently unknown. In an attempt to understand the mechanisms leading to the modification of the measured intensity, we have modeled Raman scattering efficiencies from first-principles. Thereby the Raman susceptibility tensor is calculated within the density functional theory following the approach proposed by Ghosez and co-workers [3]. The approach is validated with the TO bulk phonon modes of A1 and E symmetry and then applied to domain boundaries. The bulk Raman intensities calculated for all possible combinations of the polarization of incoming and scattered photons are in good agreement with the measured spectra. Results for simplified domain wall models are presented and discussed. [1]P. S. Zelenovskiy et. al., Appl. Phys. A 99, 741 (2010). [2]G. Berth et al., Ferroelectrics 420, 44 (2011). [3]M. Veithen et al., Phys. Rev. B 71, 125107 (2005).