Interface-induced effects on the polarization response of epitaxial ferroelectric thin films—an experimental study and theoretical analysis

Interfaces can play an important role in the properties of ferroelectric devices, which effects especially show up in devices with thin ferroelectric layers. Here we describe the measured changes in the slanting, coercive, and self-bias field of the hysteresis loop as function of the thickness of the epitaxially grown PbZr0.52Ti0.48O3 layer in capacitors with SrRuO3 electrodes on (001)-oriented SrTiO3 substrates. Models, available from literature, are discussed that explain the observed features. All observations can be attributed to the presence of a nonswitchable, dielectric and charged, strain-gradient layer at the bottom electrode interface. This study shows experimentally and theoretically the importance of the nature of the ferroelectric–electrode interfaces for the capacitor behavior and the role of strain and strain-relaxation caused by lattice mismatch and growth. We expect that the conclusions drawn from this study can be generalized to other material systems.