Micro-Brillouin Scattering of Normal and Relaxor Ferroelectrics

The micro-Brillouin scattering spectroscopy (MBSS) has been achieved by the combination of a tandem multipass Fabry-Perot interferometer and an optical microscope to probe the gigahertz to terahertz dynamics focusing on a selected microscopic area or a very small crystal. It gives new insights into the fundamental physics on the variety of vibration, relaxation processes and elementary excitations related to the instability of structural phase transitions, especially ferroic phase transitions. In the mechanism of ferroelectric phase transitions, important problems are still unsolved such as the coexistence/crossover of displacive and order-disorder dynamics, the precursor phenomena of polar regions at nanometer scale, etc. This review highlights the recent progress on the observation and understanding of high frequency dynamics for typical normal and relaxor ferroelectrics.