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Polariton‐ and directional dispersion of polar modes in orthorhombic KNbO 3 investigated by light scattering
Author(s) -
Winter F. X.,
Wiesendanger E.,
Claus R.
Publication year - 1975
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220720120
Subject(s) - polariton , orthorhombic crystal system , dispersion (optics) , phonon , condensed matter physics , polar , physics , scattering , dispersion relation , optics , molecular physics , diffraction , quantum mechanics
Experimental data on polaritons of type A 1 (TO), B 1 (TO), and B 2 (TO) in orthorhombic KNbO 3 with wave vectors propagating in the xy‐, yz ‐ and xz ‐planes, respectively, have been compared with dispersion curves calculated on the basis of the phonon data. Data on mixed mode polaritons to type B 1 + B 2 , A 1 , + B 2 , and A 1 + B 1 in the xy‐, yz ‐and xz ‐planes are shown to fit numerically calculated corresponding dispersion curves. Finally all directional dispersion branches of polaritons in the phonon limit ( k → ∞) are calculated for the three symmetry planes. Experimental data on the 45°‐phonons are presented in order to check the theoretical curves.