Interaction between quantum paraelectricity and ferroelasticity inSrTiO3

Abstract

The dielectric susceptibility of SrTiO3 is measured as a function of temperature between room temperature and 32 K. These data showan anomaly at approximately 105 K, which is associated with the cubic–tetragonal ferroelasticphase transition. The form of this anomaly is shown to be consistent with biquadratic couplingbetween the ferroelectric and ferroelastic modes. The quantum paraelectric state ofSrTiO3 is studied in the framework of a quantum mechanical Landau potential. Thesaturation temperature is determined from published measurements of the dielectricsusceptibility at very low temperatures. When the coupling to the ferroelastic mode isaccounted for, the saturation temperature obtained from these measurements(θS = 20(1) K) is the same as that seen in phase diagrams for the ferroelectric transition, such asTC versus chemical dopant or O isotope content.