Imaging of out-of-plane interfacial strain in epitaxial PbTiO3∕SrTiO3 thin films

Abstract

In this study, we rely on low-angle annular dark-field scanning transmission electron microscopy to probe the interface strain profile in epitaxial PbTiO3∕SrTiO3 thin-films. All samples displayed a compressively strained layer at the PbTiO3∕SrTiO3 interface, with the strain vector parallel to the polarization direction. The width of the strained layer was found to be ∼15–30Å, dependent on the electrode environment. Our findings open a perspective to use interface strain engineering in combination with control of electrostatic boundary conditions as a tool to monitor the effective interface polarization. These findings have implications for future use of ferroelectrics in electronic and mechanical devices.