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DF: Dielektrische Festkörper

DF 10: Electric, Electromechanical and Optical Properties I

DF 10.2: Vortrag

Donnerstag, 30. März 2006, 15:10–15:30, M{\"U}L Elch

Structuring of ferroelectric volume domains in lithium niobate crystals by space charge fields — •Felix Kalkum, Helge A. Eggert, and Karsten Buse — Institute of Physics, University of Bonn, Wegelerstr. 8, 53115 Bonn

The controlled structuring of ferroelectric domains in lithium niobate crystals promises a variety of new optical applications, e.g., electrically switchable Bragg filters. The quality of domain structures made by conventional methods is not sufficient for most of these applications. Therefore the so-called method of electrical fixing was studied: After a space charge field is written in iron doped lithium niobate crystals by means of the photorefractive effect, an external electrical field is applied. Since the resulting electrical field is above the threshold field for ferroelectric domain inversion in some regions and below in others, domains can be structured. A stochastical description of domain inversion assumes that the electrical field increases the probability for inversion, but does not imply necessarily a domain inversion if it exceeds the coercive field. The stochastical approach explains the shape and the effective modulation degree of the domain patterns. *Financial support by the DFG (BU913/11) and by the Deutsche Telekom AG is gratefully acknowledged.