title: Role of polar nanoregions with weak random fields in Pb-based perovskite ferroelectrics.
abstract: In relaxor ferroelectrics, the role of randomly orientated polar nanoregions (PNRs) with weak random fields (RFs) is one of the most puzzling issues of materials science. The relaxation time of polarization fluctuations of PNRs, which manifests themselves as a central peak (CP) in inelastic light scattering, is the important physical quantity to understand the dynamics of PNRs. Here, the angular and temperature dependences of depolarized and polarized CPs in 0.44Pb(Mg1/3Nb2/3)O3-0.56PbTiO3single crystals with weak RFs have been studied by Raman and Brillouin scattering, respectively. The CPs observed in Raman scattering show the very clear angular dependence which is consistent with the local tetragonal symmetry. It is different from the well-known local rhombohedral symmetry with strong RFs for Pb(Mg1/3Nb2/3)O3. In Brillouin scattering, depolarized and polarized CPs show two relaxation processes corresponding to transverse and longitudinal fluctuations of PNRs. The remarkable slowing down towards the Curie temperature was observed for transverse fluctuations in local tetragonal symmetry.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan.|Department of Physics, Begum Rokeya University, Rangpur, Rangpur, 5400, Bangladesh.
authors.forename: M A
authors.initials: MA
authors.lastname: Helal
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan.|Department of Physics, Pabna University of Science and Technology, Pabna, 6600, Bangladesh.
authors.forename: M
authors.initials: M
authors.lastname: Aftabuzzaman
authors.affiliation: Faculty of Education, Shimane University, Matsue, Shimane, 690-8504, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tsukada
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kojima