Dresden 2011 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 12: Poster

DF 12.13: Poster

Mittwoch, 16. März 2011, 15:00–17:30, P1

Thermal polarization noise of silver sodium nitrite — •Jumna Mehlis, Ulrich Straube, Martin Diestelhorst, Jörn Petersson, and Horst Beige — Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Germany

The thermal polarization fluctuations of ferroelectric crystals in the vicinity of the phase transition are discussed in detail in thermo-dynamic theories. These could be observed experimentally in a ferroelectric liquid crystal [1]. However, there is no publication about the experimental proof of the polarization noise in solid ferroelectric crystals. For this reason it was our aim to prove the spontaneous fluctuations of the polarization field in a ferroelectric AgNa(NO2)2-crystal. This was achieved by measurements of the thermal current noise in short * circuit of the single crystal. The noise current was made measurable with the help of a current - voltage amplifier. The thermal polarization and current noise power spectra of the silver sodium nitrite crystal could be described by the generalized Nyquist theorem. The possibility to determine the phase transition by noise measurements is discussed.

[1] I. Musevic, A. Kityk, M. Skarabot, and R. Blinc, Phys. Rev. 79, 1062-1065 (1997).