Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 4: Multiferroics, Phase Transitions & Relaxors

DF 4.3: Talk

Monday, March 23, 2009, 11:00–11:20, WIL B321

Dimensional crossover and absence of quantum criticality in SrTi¹⁶O_1−x¹⁸O_x — •Annette Bussmann-Holder¹ and Alan R. Bishop² — ¹Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart — ²Los Alamos National Laboratory, Theoretical Division, Los Alamos NM887545, USA

The isotope-induced ferroelectricity observed in SrTi¹⁸O₃ (STO18) enables a systematic study of the crossover between quantum paraelectricity and ferroelectricity as a function of x in SrTi¹⁶O_1−x¹⁸O_x (STO16_1−xSTO18_x). We predict that all ferroelectric compounds have a finite transition temperature Tc and show a dimensionality crossover from d=3 to d=4 at sufficiently low temperature. A discontinuity in behavior takes place around x=0.35, where quantum fluctuations suppress the transition. No evidence is found for a quantum critical point in the phase diagram. The high temperature structural transition shows a substantial isotope dependence which is, however, less striking than for the ferroelectric transition.