Brillouin Scattering Study of the Anisotropic Relaxation of the Polarization Fluctuation in Ferroelectric TGS

Abstract

The polarization relaxation phenomena in the uniaxial ferroelectric TGS have been studied by the observation of the angular dependence of the Brillouin scattering spectra. Both the frequency shift and the full width of the Brillouin satellite show remarkable anisotropic anomalies most strongly at 44.94°C below the transition temperature T c =48.86°C. The experimental result is successfully interpreted from the viewpoint of the depolarization effect on the polarization fluctuation. The effect is characterized by the anisotropic relaxation time with only two parameters ; a relaxation time τ 0 for a transverse polarization fluctuation and a generalized Lorentz factor L . The values τ 0 =(0.93±0.09)×10 -11 sec and L ≃0.41 give a good description of the experimental result.