Thickness Dependence of Domain-Wall Patterns in BiFeO₃ Thin Films

Abstract

Unique properties of domain walls in ferroelectrics have been recently discovered but methods of their controlled engineering remain underdeveloped. Here we investigate the domain structure of Bi_0.9La_0.1FeO₃ epitaxial thin films with piezoelectric force microscopy and transmission electron microscopy. We show that with increasing Bi_0.9La_0.1FeO₃ thickness, a transition from randomly-oriented 71° domain walls to 109° domain walls stripe occurs. At intermediate thicknesses, 71° and 109° domain walls coexist together with non-ferroelastic 180° domain walls. TEM cross-section images show complex domain structure due to the interplay between electrostatic constrains imposed by the SrRuO₃ electrode and mechanical constrains imposed by the DyScO₃ substrate.

Keywords:

• BiFeO₃
• PLD
• PFM
• domain structure
• thin film

Funding

The research leading to these results has received funding from the European Research Council under the EU 7th Framework Program (FP7/2007–2013)/ERC grant agreement no (268058) Mobile-W for the purchase of equipment and from Lithuanian-Swiss cooperation programme to reduce economic and social disparities within the enlarged European Union under project agreement No. CH-3-ŠMM-01/02 for the purchase of conductive AFM tips and substrates. The Swiss National Science Foundation (Grant number 200020_144454) is acknowledged for additional financial support used for TEM characterization.