Dresden 2006 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.29: Poster

Montag, 27. März 2006, 09:30–17:00, P1

Metastable polar structures in the uniaxial relaxor Sr_0.61Ba_0.39Nb₂O₆:Ce studied by piezoresponse force microscopy — •Vladimir V. Shvartsman and Wolfgang Kleemann — Angewandte Physik, Universität Duisburg-Essen, 47048 Duisburg

Strontium-barium titanate Sr_xBa_1−xNb₂O₆ (SBN) based materials comprise a special group of relaxor ferroelectrics, which belong to the random-field Ising model (RFIM) universality class [1]. In accordance with the theory of 3D RFIM systems a metastable multidomain state appears on cooling through T_c, which is expected to relax slowly in time towards the single domain state [2]. We present the results of studies of the polar structures in a SBN single crystal doped with cerium (SBN:Ce) by piezoresponse force microscopy. The appearance of fractal-like nanodomains was found on cooling from the paraelectric state. These nanodomains are metastable and grow slowly in the course of time according to a logarithmic law as predicted [2]. At elevated temperatures the decay of the nanodomains takes place, but even above T_c areas of correlated polarization were observed. We suggest that they correspond to agglomerates of polar nanoregions formed via the ferroelectric mean-field of the system.

1. W. Kleemann, J. Dec, P. Lehnen, R. Blinc, B. Zalar, R. Pankrath, Europhys. Lett. 57, 14 (2002).

2. J. Villain, Phys. Rev. Lett. 52, 1543 (1984).