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DF: Dielektrische Festkörper

DF 4: Keramiken, Gradientenwerkstoffe und Relaxoren

DF 4.4: Talk

Tuesday, March 12, 2002, 15:50–16:10, 11

Dielectric response, second-harmonic generation and random-field induced domain wall response of SrTi¹⁸O₃ — •Lei Zhang¹, Wolfgang Kleemann¹, Jan Dec¹, Peer Lehnen¹, Ruiping Wang², and Mitsuru Itoh² — ¹Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, 47048 Duisburg — ²Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan

The dielectric permittivity є’-iє” and optical second-harmonic generation (SHG) of SrTi¹⁸O₃ are studied under a dc electric field E as a function of the temperature, T. In є’ vs. T, a double-peak is found when 0 < E < 30kV/m. While the peak at high-T is attributed to the smeared ferroelectric phase transition, the low-T one is induced by domain wall motion. Optical SHG shows that the SrTi¹⁸O₃ develops polar regions on cooling towards the phase transition at T_c ≈ 24K. The transverse Ising model including an external homogeneous and quenched random-fields is successfully used to describe both the smeared phase transition and the domain wall response in the low-T domain state.