Thickness Dependence of Phase Transition Temperature in Disordered Monodomain Ferroelectric Thin Films

摘要

We propose a theoretical approach to calculate the thermodynamic properties of thin films fabricated from monodomain disordered ferroelectrics. We do that for the incipient ferroelectrics with dipole impurities like KTaO_3: Li, Nb, Na or SrTiO_3 Ca, although the proposed approach can be also applied to ferroelectric relaxors. In our calculations we use the method of random fields, modified for the case of confined geometry. The essence of modification is the altering of the interaction between impurity dipoles by geometrical confinement. We show that in thin films the ferroelectric phase transition is inhibited as compared to the case of bulk samples.