Strain Tuning of Ferroelectric Thin Films

TLDR

Predictions and measurements of biaxial strain effects on epitaxial ferroelectric thin films and superlattices are reviewed. The authors apply first‑principles, thermodynamic, and phase‑field models to biaxially strained ferroelectric films, compare predictions with experiments, and outline key experimental techniques and suitable substrates. Measurements show that percent‑level biaxial strain shifts the paraelectric‑to‑ferroelectric transition temperature by hundreds of degrees, confirming predictions, and results for single‑layer and superlattice films of SrTiO₃, BaTiO₃, and PbTiO₃ are presented.

Abstract

Predictions and measurements of the effect of biaxial strain on the properties of epitaxial ferroelectric thin films and superlattices are reviewed. Results for single-layer ferroelectric films of biaxially strained SrTiO 3 , BaTiO 3 , and PbTiO 3 as well as PbTiO 3 /SrTiO 3 and BaTiO 3 /SrTiO 3 superlattices are described. Theoretical approaches, including first principles, thermodynamic analysis, and phase-field models, are applied to these biaxially strained materials, the assumptions and limitations of each technique are explained, and the predictions are compared. Measurements of the effect of biaxial strain on the paraelectric-to-ferroelectric transition temperature (T C ) are shown, demonstrating the ability of percent-level strains to shift T C by hundreds of degrees in agreement with the predictions that predated such experiments. Along the way, important experimental techniques for characterizing the properties of strained ferroelectric thin films and superlattices, as well as appropriate substrates on which to grow them, are mentioned.