Abstract
Resonant ultrasound spectroscopy has been used to follow elastic softening in in the frequency range . A dramatic softening of occurs as the Curie temperature is approached from above or below, which correlates with the development of a central peak in Raman and Brillouin spectra. This is attributed to strong coupling between the acoustic mode and the central peak mode. A weaker anomaly is seen in a resonance mode which is believed to be controlled by . Significant attenuation accompanies this softening and an additional dissipation peak has also been observed at . This extends earlier work by a factor of from the 30 GHz regime and helps address the question as to whether the ferroelectricity is stimulated primarily by a soft mode into a homogeneous ground state or by clustering of rhombohedral nanoregions into an inhomogeneous ground state.
- Received 18 November 2010
DOI:https://doi.org/10.1103/PhysRevLett.106.105502
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