可用于纳电子器件的铁电畴壁新颖物理特性探索

In recent years, with the development of nano-detection technology, researchers have gradually realized that domain walls, different from domains, could be independent functional units for nanoelectronic devices. Up to now, however, the limited studies focusing on domain walls are less compressive and indepth, and many problems have not been revealed and solved. In this project, we plan to explore the inherent mechanism of domain wall conductance through comparing different types of domain walls in a variety of ferroelectric materials, put forward reasonable scheme for preparing stable conductive domain walls after investigating the effect of polarization direction, pn type, size and stress on the dynamics of domain walls, inspect the mobility and conductivity of domain walls under different aggregation states, and hope to further achieve some new findings on the physical properties of ferroelectric vortices. Finally, we will propose a generalized theoretical model for domain wall conductance, and this study could enrich the connotation of topology in physics.

近年来，随着纳米检测技术的发展，人们逐渐认识到，畴壁，区别于畴区，可以成为纳电子器件独立的功能单元。但是目前聚焦于畴壁自身的研究尚不够系统和深入，很多问题没有揭示和解决。本项目计划通过对比多种铁电材料中不同类型畴壁的电导现象，揭示畴壁电导的内在机制；研究畴壁两侧极化方向、样品pn型、尺寸及应力等因素对畴壁动性的影响，提出制备稳定导电畴壁的合理方案；最后考察畴壁不同聚集状态下的畴壁动性和导电特性，并力争进一步揭示与铁电涡旋相关的电、磁、力、光新现象。本项目将提出可推广的用于畴壁电导的理论模型，同时为拓扑物理学研究提供更加丰富的内涵。

铁电材料中导电畴壁和极性拓扑结构因其在纳电子领域的可能应用前景而成为近年来的研究热点，但是它们的微观可操控性和相关内在机制问题并没有解决。本工作围绕重要的多铁性BiFeO3外延薄膜和弛豫铁电PMN-28PT晶体开展研究工作，主要成果包括：（1）深入分析了不同导电类型畴壁的动力学特征，揭示了畴壁动性与其导电类型的内在联系，并在此基础上设计了制备整齐而稳定导电畴壁阵列的有效方案。（2）发现高温淬火能改变三方/四方混合相薄膜中的相组成，进而改变电畴结构以及材料机械硬度，揭示了热力学条件的精细控制对铁电材料微观结构的重要影响。（3）展示了光诱导铁电拓扑结构演变的新现象，结合光刻技术制备出中心汇聚型拓扑畴阵列，提出了合理的物理图像。该项目成果对基于畴壁和极性拓扑结构的电子器件的开发和实际应用有重要参考价值。项目执行期间在Natl. Sci. Rev.、Phys. Rev. Lett.、Adv. Optical Mater.等刊物发表SCI论文20篇。