Central Peak in SrTi18O3 Studied by Light Scattering

Abstract

A central peak (CP) has been found mainly in the VH light scattering spectra of SrTi(18 O 0.87 16 O 0.13)3 (87% 18O-exchanged SrTiO3). Both of the intensity and relaxation time of the CP show broad peaks around T m ≈ 22 K (below the transition temperature T c ≈ 25 K). The physical origin of the CP is determined not to be the polarization fluctuation, representing that this CP is not a sign of a phase transition of order-disorder type. The stochastic fluctuation of the spatial derivatives of the polarization would be the physical origin of the CP.