Department of Materials Science and Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States.
Nano Lett. 2013 Nov 13;13(11):5218-23. doi: 10.1021/nl402651r. Epub 2013 Oct 3.
Charged domain walls (CDWs) are of significant scientific and technological importance as they have been shown to play a critical role in controlling the switching mechanism and electric, photoelectric, and piezoelectric properties of ferroelectric materials. The atomic scale structure and properties of CDWs, which are critical for understanding the emergent properties, have, however, been rarely explored. In this work, using a spherical-aberration-corrected transmission electron microscope with subangstrom resolution, we have found that the polarization bound charge of the CDW in rhombohedral-like BiFeO3 thin films not only induces the formation of a tetragonal-like crystal structure at the CDW but also stabilizes unexpected nanosized domains with new polarization states and unconventional domain walls. These findings provide new insights on the effects of bound charge on ferroelectric domain structures and are critical for understanding the electrical switching in ferroelectric thin films as well as in memory devices.
带电畴壁（CDWs）具有重要的科学和技术意义，因为它们在控制铁电材料的开关机制以及电、光电和压电性能方面起着关键作用。然而，对于理解新兴特性至关重要的 CDWs 的原子尺度结构和性质却很少被探索。在这项工作中，我们使用具有亚埃分辨率的球差校正透射电子显微镜发现，在类菱面体 BiFeO3 薄膜中的 CDW 的极化束缚电荷不仅诱导 CDW 处形成四方型类似的晶体结构，而且还稳定了具有新极化状态和非常规畴壁的纳米级尺寸的畴。这些发现为束缚电荷对铁电畴结构的影响提供了新的见解，对于理解铁电薄膜以及存储器件中的电开关至关重要。
