Berlin 2005 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 9: Phasenüberg
änge und Spektroskopie

DF 9.3: Vortrag

Dienstag, 8. März 2005, 11:00–11:20, TU EMH225

Creep and relaxation dynamics of domain walls in periodically poled KTiOPO₄ — •Wolfgang Kleemann¹, Thomas Braun¹, Jan Dec^1,2, and Pamela A. Thomas³ — ¹Angewandte Physik, Universität Duisburg-Essen, 47048 Duisburg — ²Institute of Physics, University of Silesia, PL 40-480 Katowice, Poland — ³Department of Physics, University of Warwick, Warwick, England

Creep and relaxation of domain walls under ac electric fields in an ideal model system, periodically-poled single-crystal KTiOPO₄, occurs in different regimes, which are separated by dynamic phase transitions at frequencies f_m(T)=f_m0exp(−Δ E/k_BT) with f_m0= 3· 10 ⁹ Hz and Δ E= 0.6 eV. Power law dispersion of the creep susceptibility, χ ∝ 1+(i ω τ )^−β with β ≈ 0.4, and large non-linearity encountered at f<f_m, is contrasted with Cole-Cole-type relaxational dispersion, χ ∝ (1+[iωτ ]^1−α )⁻¹ with α ≈ 0.3 at f>f_m.