Untangling Electrostatic and Strain Effects on the Polarization of Ferroelectric Superlattices

• Published in: Advanced functional materials Vol. 26; no. 35; pp. 6446 - 6453
• Main Authors: Khestanova, Ekaterina, Dix, Nico, Fina, Ignasi, Scigaj, Mateusz, Rebled, José Manuel, Magén, César, Estradé, Sonia, Peiró, Francesca, Herranz, Gervasi, Fontcuberta, Josep, Sánchez, Florencio
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.09.2016; Wiley-VCH
• Subjects: BaTiO3; Boundary conditions; Electrostatics; epitaxy; Ferroelectric materials; ferroelectric superlattices; Ferroelectricity; Metallic oxides; Multilayers; oxides; Pel·lícules fines; Polarization; Strategy; Superlattices; Thin films; Òxids metàl·lics
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201602084

The polarization of ferroelectric superlattices is determined by both electrical boundary conditions at the ferroelectric/paraelectric interfaces and lattice strain. The combined influence of both factors offers new opportunities to tune ferroelectricity. However, the experimental investigation of their individual impact has been elusive because of their complex interplay. Here, a simple growth strategy has permitted to disentangle both contributions by an independent control of strain in symmetric superlattices. It is found that fully strained short‐period superlattices display a large polarization whereas a pronounced reduction is observed for longer multilayer periods. This observation indicates that the electrostatic boundary mainly governs the ferroelectric properties of the multilayers whereas the effects of strain are relatively minor. The modulation of properties in ferroelectric superlattices comes from electrostatic boundary conditions and cell distortions associated with interface‐controlled epitaxial strain, but there is no clear picture of the specific relevance of each of these factors. Using a simple growth strategy, a separate control is achieved, allowing disentangling the relative contribution of electrostatic boundary conditions and strain. It turns out that the former rules the ferroelectric response, meanwhile the influence of the lattice strain is of secondary relevance.