Enhanced switching characteristics and piezoelectric response in epitaxial BiFeO3–TbMnO3 thin films

• (001) oriented epitaxial 0.9BiFeO3–0.1TbMnO3 thin films were deposited.
• Upward ferroelectric self-poling was observed in the epitaxial thin films.
• Compressive strain gradient is responsible to the self-polarization.

High-quality (001) oriented epitaxial 0.9BiFeO3–0.1TbMnO3 thin films were grown on La2/3Sr1/3MnO3 and SrRuO3 buffered SrTiO3 substrate using pulsed laser deposition. X-ray diffraction showed that the films are single-phase perovskite without secondary impurity phases. Domain structures and upward ferroelectric self-poling phenomenon were distinctly observed in both films with compressive epitaxial strains. Furthermore, the upward self-poling disappears in polycrystalline 0.9BiFeO3–0.1TbMnO3 thin film on Pt/TiO2/SiO2/Si substrates. Through local switching spectroscopy measurements, the evidence of enhanced ferroelectric switching and piezoelectric response characteristics have been provided.