Berlin 2024 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 27: Polar oxides: Lithium niobate and lithium tantalate
KFM 27.4: Talk
Thursday, March 21, 2024, 16:00–16:20, TC 010
Vibrational and optical properties of LiNbO3 and LiTaO3 under uniaxial stress — •Mike Pionteck1, Matthias Roeper2, Ekta Singh2, Boris Koppitz2, Sven Reitzig2, Michael Lange2, Sam Seddon2, Michael Rüsing2,3, Laura Padberg3, Simone Sanna1, and Lukas Eng2,4 — 1Institut für Theoretische Physik, Center for Materials Research (LaMa), Justus-Liebig-Universität Gießen, 35392 Gießen, Germany — 2Institut für Angewandte Physik, Technische Universität Dresden, 01062 Dresden, Germany — 3Paderborn University, Integrated Quantum Optics, Institute for Photonic Quantum Systems (PhoQS), Warburger Str. 100, 33098 Paderborn, Germany — 4ct.qmat: Dresden-Würzburg Cluster of Excellence - EXC 2147, TU Dresden, 01062 Dresden, Germany
Our work provides, for the first time, a theoretical description of phonon frequencies of LiNbO3 and LiTaO3 under uniaxial stress along Cartesian axes using density functional theory (DFT). The calculations show a roughly linear dependence of the Raman frequencies on the applied uniaxial stress, which is confirmed by corresponding Raman measurements [1]. Additionally, we model linear and non-linear optical properties of LiNbO3 in dependence on uniaxial stress using time-domain DFT. We find roughly linear changes for all components of the second harmonic generation under uniaxial stress. From the calculated dielectric tensor under stress, the dispersion of the piezo-optic and photoelastic coefficients are obtained. [1] E. Singh et al. Phys. Rev. Mat. 7, 024420 (2023).
Keywords: Ferroelectrics; Density functional theory; Stress; Strain; Raman spectroscopy