Critical dielectric relaxation of highly deuterated betaine arsenate at microwave frequencies |
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Authors: | H J Brückner |
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Institution: | (1) Fachbereich Physik der Universität des Saarlandes, Saarbrücken, Federal Republic of Germany;(2) Fernmeldetechnisches Zentralamt, Am Kavalleriesand 3, D-6100 Darmstadt, Federal Republic of Germany |
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Abstract: | The dielectric behavior of highly deuterated betaine arsenate in the frequency range up to 11 GHz is described by a Cole-Davidson relaxation. The characteristic dynamics show a critical slowing down near the para-antiferroelectric phase transition. The temperature dependence of the dielectric constant is analyzed in terms of a pseudo-one-dimensional Ising model. Evidence is given for a dependence of antiferroelectric coupling on deuteration which can explain the change from a ferro- to an antiferroelectric ordering on deuteration. Measurements of the dielectric relaxation under a dc bias field parallel to the critical axis elucidate the unusual phase transition behavior at low temperatures. A multicritical point appears in theE-T-phase diagram. Frustration effects due to competing ferro- and antiferroelectric interactions are not seen. |
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