title: Dynamics of nanoscale polarization fluctuations in a uniaxial relaxor.
abstract: We have studied neutron diffuse scattering in a Sr(0.61)Ba(0.39)Nb(2)O(6) single crystal by neutron backscattering at sub-μeV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Praha 8, Czech Republic.
authors.forename: P
authors.initials: P
authors.lastname: Ondrejkovic
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Praha 8, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Kempa
authors.affiliation: Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: J
authors.initials: J
authors.lastname: Kulda
authors.affiliation: Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: B
authors.initials: B
authors.lastname: Frick
authors.affiliation: Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Appel
authors.affiliation: Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: J
authors.initials: J
authors.lastname: Combet
authors.affiliation: Institute of Materials Science, University of Silesia, Bankowa 12, PL-40-007 Katowice, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Dec
authors.affiliation: Institute of Electronic Materials Technology, 133 Wolczynska Street, 01-919 Warsaw, Poland.
authors.forename: T
authors.initials: T
authors.lastname: Lukasiewicz
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Praha 8, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Hlinka