Chemical-Strain-Engineered Adaptive Interfaces in Nanocomposite Films for Robust Ferroelectricity

Abstract

Strain is an effective means of tuning the crystal structure to obtain a variety of fascinating properties, but how to apply flexible strain to meet the different needs of the film at each location has rarely been reported. In this study, a novel approach for designing strain-damping structures that facilitate the imposition of flexible strain is introduced. A wide range of strain modulation is demonstrated in SmCoO₃ films (a-axis:+4.5%–+1.7%, b-axis: +3.2%–+0.4%, c-axis:+2.2%–+1.4%) under positive pressure by introducing Sm₂O₃ as a dopant. When SmCoO₃ films are subjected to triaxial tensile strain, they exhibit a ferroelectric polarization of 7.12 µC cm⁻². Through positive pressure modulation, resulting in a further increase in the ferroelectric polarization (up to 11.62 µC cm⁻², which represents the maximum performance of the orthogonal rare earth transition metal oxide family). Moreover, the electron spin order can be effectively controlled, and the film's saturation magnetization increases to 14.83 emu cm⁻³ (+94.1%). This damping structure allows for flexible modulation of chemical strain in epitaxial film, achieving a delicate balance between film strain and structure, which provides valuable insights for all ferroelectrics based on structural distortion.