Abstract
Hyper-Raman scattering experiments suggest that a splitting of the lowest -symmetry mode of crystal occurs in a wide temperature range around its Burns temperature . The upper-frequency component, earlier investigated by inelastic neutron scattering experiments above , appears to be underdamped even hundred of degrees below . The lower-frequency component, known below from far-IR spectroscopy, actually becomes underdamped above . This suggests that the lower-frequency mode is the “primary” polar soft mode of , responsible for the Curie-Weiss behavior of its dielectric permittivity above .
- Received 4 February 2010
DOI:https://doi.org/10.1103/PhysRevLett.105.017601
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