Department of Chemical Engineering and Materials Science, University of California - Irvine , Irvine, California 92697, United States.
National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University , Nanjing, Jiangsu 210093, China.
Nano Lett. 2017 Jun 14;17(6):3556-3562. doi: 10.1021/acs.nanolett.7b00696. Epub 2017 May 11.
The ability to switch the ferroelectric polarization using an electric field makes ferroelectrics attractive for application in nanodevices such as high-density memories. One of the major challenges impeding this application, however, has been known as "retention failure", which is a spontaneous process of polarization back-switching that can lead to data loss. This process is generally thought to be caused by the domain instability arising from interface boundary conditions and countered by defects, which can pin the domain wall and impede the back-switching. Here, using in situ transmission electron microscopy and atomic-scale scanning transmission electron microscopy, we show that the polarization retention failure can be induced by commonly observed nanoscale impurity defects in BiFeO thin films. The interaction between polarization and the defects can also lead to the stabilization of novel functional nanodomains with mixed-phase structures and head-to-head polarization configurations. Thus, defect engineering provides a new route for tuning properties of ferroelectric nanosystems.
利用电场改变铁电极化的能力使得铁电体在纳米器件（如高密度存储器）中具有吸引力。然而，阻碍这一应用的主要挑战之一被称为“保持失败”，这是极化反转的自发过程，可能导致数据丢失。这个过程通常被认为是由界面边界条件引起的畴不稳定引起的，而缺陷可以钉住畴壁并阻碍反转。在这里，我们使用原位透射电子显微镜和原子尺度扫描透射电子显微镜，表明在 BiFeO 薄膜中常见的纳米级杂质缺陷可以引发极化保持失败。极化与缺陷之间的相互作用也可以导致具有混合相结构和头对头极化构型的新型功能纳米畴的稳定。因此，缺陷工程为铁电纳米系统的性能调谐提供了一条新途径。
