BiFeO3外延薄膜挠曲电效应调控及其对磁电性能增强机理研究

项目名称： BiFeO3外延薄膜挠曲电效应调控及其对磁电性能增强机理研究

项目编号： No.51472078

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 祁亚军

作者单位： 湖北大学

项目金额： 83万元

中文摘要： 多铁性BiFeO3 (BFO)外延薄膜在相界区域应变梯度高达1E7/m，与其巨大的剩余极化(>100 uC/cm2)耦合，可产生显著的挠曲电效应，这为BFO磁电性能调控及其应用提供新的思路和方法，受到人们极大关注。本项目拟通过改变生长工艺调控薄膜中的应变梯度，研究挠曲电效应对BFO外延薄膜宏观磁电性能的影响，建立薄膜应变梯度的大小与宏观性能的关联；采用原位高分辨透射电子显微术，从原子尺度研究薄膜中的界面(相界、畴界、缺陷)附近的挠曲电效应，测量应变梯度大小，计算挠曲电极化和挠曲电系数的大小，探索基于挠曲电效应实现机械应力控制铁电纳米畴开关的技术方法和物理机制，得到应变梯度与电极化耦合的直接证据；探索挠曲磁和挠曲磁电效应，获得利用挠曲磁电效应增强磁电耦合的技术手段，结合唯象理论计算，揭示挠曲磁电耦合增强磁电效应的物理机制，为BFO在光电信息领域的应用提供理论指导和实验依据。

中文关键词： 挠曲电效应；磁电耦合；BiFeO3；外延薄膜

英文摘要： The development of nanoscale technologies has attracted great interests in flexoelectricity, as the large strain gradients often present at the nanoscale can lead to strong flexoelectric effects. According to previous reports, one may expected that there will be large flexoelectric effects at the phase boundaries in BiFeO3 (BFO) epitaxial thin film due to the giant strain gradient (1E7/m) and polarization (>100 uC/cm2), which will shed some light on mechanisms for enhanced electromechanical coupling and its applications. In this proposal, we plan to investigate the effects of flexoelectric coupling on the magnetic and electrical properties of BFO thin films with strain gradients. The flexoelectric effects at the interface (eg. phase boundaries, domain walls and dislocation cores) will be revealed in the atomic scale by measuring the flexoelectric polarization and the flexoelectric coefficients with a high resolution transmission electron microscopy. We also plan to explore the mechanisms of flexoelectric switching of ferroelectric nanodomains and find effective ways to control the flexoelectric switching. The flexomagnetic effect and flexomagnetoelectric effect of BFO thin films will be investigated. We try to find effective ways to tune the magnetoelectric coupling through flexomagnetic and flexomagnetoelectric effects. Combining experimental results with theoretical ones, the mechanisms for magnetic, electrical properties enhancements should be revealed. The results of this project will support the flexoelectricity application of epitaxial BFO thin films.

英文关键词： flexoelectric effects;magnetoelectric coupling;BiFeO3;epitaxial thin films