Thickness Dependence of c/a Polytwin Structures Observed in Epitaxial Oxide Ferroelectric Thin Films

Authors: S. PAMİR ALPAY, ALEXANDER L. ROYTBURD

Abstract: Ferroelectric or ferroelastic epitaxial films undergoing a cubic-to-tetragonal phase transformation usually relax the resultant strain energy due to lattice misfit by forming a polytwin (polydomain) structure. Polydomain formation occurs at the expense of building interdomain interfaces and microstresses which develop at the film-substrate interface due to the periodic deviation of the strain. The interplay between these components results in a critical thickness for domain formation below which the polydomain structure is not stable. In this article, we investigate the film thickness dependence of a polydomain structure using a thermodynamical approach.

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