作为一种重要磁电功能材料，复合多铁性化合物的界面结构优化是提高其机械能-电能-磁能相互转化效率以满足诸多新型功能器件性能需求的关键基础。相界面应变调控新方法为新型复合多铁性化合物的设计、界面结构优化和性能提升提供了新的机会。本项目拟以相界面应变调控方式为主要研究思路，探索铁电相-铁磁相共格相界面的化学设计和合成方法，实现复合多铁性薄膜多铁性能和磁电耦合性能的调控和优化提升，并通过改变铁电相和铁磁相的选择、相界面构型和分布等方式探索建立相界面应变调控多铁性能的有效方法。在此基础上，借助于现代电子显微学方法，通过在原子尺度下对界面结构和多铁性参数的定量测量，深入探讨相界面应变调控提升多铁性的微观机制，揭示界面结构与多铁性能和磁电耦合性能的构效关系机理。该项目的开展不仅有助于获得性能优异的多铁性化合物及清晰的界面调控多铁性机理，而且有望为新型多铁性化合物的设计、合成和性能优化提供重要参考依据。

As an important type of magnetoelectric functional material, the multiferroic composite when with its interface structure optimized can have superior conversion efficiency among mechanical, electrical and magnetic energies, and therefore, will meet the performance requirements in a wide range of novel functional devices. In this aspect, the newly developed interphase strain method provides more opportunities for the design, interface structure optimization and magnetoelectric performance improvement of multiferroic composites. Here, by taking full advantage of the interphase strain method, we will first systematically study the chemical design and synthesis method to achieve the coherent interphase between ferroelectric and ferromagnetic phases, realizing the improvements of multiferroic and magnetoelectric coupling performance in multiferroic composite thin films. Then, the influences of the types of ferroelectric and ferromagnetic phases, interphase configurations and distributions on magnetoelectric coupling will be investigated, yielding the effective interphase strain modulation strategies. Furthermore, the interphase structure and multiferroic parameters will be quantitatively measured at the atomic scale using advanced electron microscopy. On this base, the microcosmic mechanism of interphase strain-induced multiferroic property promotion will be clarified and the intrinsic relationship between interphase structure and multiferroic properties will be revealed. With the realization of superior-performance multiferroic compounds and unambiguous interphase strain modulation mechanisms, this project can provide important experimental and theoretical supports for the design, synthesis and performance optimization for new types of multiferroic systems.