Regensburg 2002 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 8: Phasenüberg
änge und Spektroskopie

DF 8.7: Vortrag

Donnerstag, 14. März 2002, 17:10–17:30, 11

Interplay between rare earth ion defects and the domain inversion in lithium niobate — •Chr. Sandmann1, V. Dierolf1, and V. Gopalan21Lehigh University, Bethlehem, PA 18015, USA — 2Penn State University, University Park, PA 16802, USA

Many details of domain inversion in ferroelectrics strongly depend on the number of intrinsic and extrinsic defects. For instance, in lithium niobate (LiNbO3) the voltage required for domain reversal is reduced by two orders of magnitude when the sample composition is modified from the common congruent to the almost defect-free stoichiometric one[1]. For the latter the domain reversal properties are particularly sensitive to doping with trivalent ions because the charge compensation requirement adds a considerable number of defects and intrinsic electric fields. On the other hand, the optical transitions of the ions such as Er3+ will reflect the changes in their defect environment taking place during domain reversal.

For the investigation of this interplay we studied Er3+-doped nearly stoichiometric LiNbO3 before and after an intial poling process by site-selective combined excitation-emission spectroscopy (CEES). We observed a significant redistribution among the various Er3+-defect types. We will discuss this phenomena in terms of previously proposed defect models[2]. The pronounced site redistribution, its ease of detection, and the advanced understanding of the underlying defect configurations makes the Er3+-defect an ideal "micro-probe" to investigate the dynamic and spatial aspects of domain inversion and motion of domain walls.

[1]V. Gopalan et al., Appl. Phys. Lett. 72, 1981 (1998)

[2]V. Dierolf, M. Koerdt, Phys. Rev.B 61, 8043 (2000)

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