Berlin 2005 – scientific programme

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DF: Dielektrische Festkörper

DF 9: Phasenüberg
änge und Spektroskopie

DF 9.5: Talk

Tuesday, March 8, 2005, 11:40–12:00, TU EMH225

Non-linear and scaling properties of the dielectric response of SrTi¹⁸O₃ in the quantum paraelectric regime — •Wolfgang Kleemann¹, Jan Dec^1,2, and Mitsuru Itoh³ — ¹Angewandte Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany — ²Institute of Physics, University of Silesia, PL 40-007 Katowice, Poland — ³Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-853

Critical behavior, scaling and non-linear properties of the susceptibility χ = χ’- iχ” in ¹⁸O isotope exchanged SrTiO₃ are revisited in a crystal, which was perfectly single domained by an external electric field in the quantum paraelectric regime above T_c≈ 24 K. Corrections due to random-field induced nanoregions turn out to be important, if not decisive, for a reliable description. We find quantum critical exponents γ ≈ 1.9± 0.1, δ ≈ 2.7± 0.1 and Δ ≈ 3.1± 0.1, and a cusplike behavior of the nonlinear coefficient B with an exponent 3γ −2Δ ≈ 0.4. Below T_c the critical and scaling analysis is inhibited by large contributions of domain walls to the susceptibility.