Intrinsic Mechanical Compliance of 90° Domain Walls in PbTiO ₃

Abstract Functionality of domain walls and other topological defects in ferroelectrics is being widely investigated for applications in electronic devices. While the intrinsic electronic properties of a wall have been considered, its inherent mechanical properties remain explored very little, despite the fact that coupling between strain and polarization is prevalent in many of these materials. Herein, an in‐depth study of variations in nanomechanical properties at 90 o domain walls and their adjacent domains in single‐crystalline lead titanate (PbTiO 3 ) is presented as a prototypical ferroelectric material using a combination of various atomic force microscopy (AFM)‐based methods. Considerable variations of elastic moduli are found at 90 o domain walls extending up to ~100 nm into the domain areas. AFM nanoindentation also allows to extract local domain wall hardness and plastic and elastic deformation energies. These findings have implications for the design of ferroelectric domain wall functionality that incorporates the intrinsic elastic compliance of a domain wall.