报告人：Dr. Er-JiaGuo（Institute of Physics, Martin-Luther-University Halle-Wittenberg, and Max-Planck-Institute for Microstructure Physics, Weinberg 2, 06120 Halle, Germany）

摘要：

Ferroelectric ordering in complex oxide films can be very sensitive to elastic strain. This has been exploited in many strain-coupled ferroelectric (FE) thin-films. The origins of strain sensitivity are multiple. Fundamentally understood and modeled strain determined processes were in rather few cases. The strain effect on the domain growth is seldom addressed due to the difficulty in comparing two defective films. In this talk, I will introduce the application of piezoelectric substrates for reversible strain control in epitaxial FE films (PZT and BFO), allowing one to study the same thin film in different strain states. Firstly, I will discuss the influence of elastic stain on the switching time of FE capacitors. Field dependent relative changes of switching time are found, which can be attributed to the dynamics of domain wall propagation. Further, we conduct the local studies of domain wall velocity by piezoresponse force microscopy in in-situ controlled strain states of the samples. Remanent circular domains showed strong strain dependences of both, domain relaxation / shrinking in zero electric field and field-driven velocity. The latter reversibly increased by an order of magnitude upon 0.13% of in-plane expansion. We discuss these findings in the light of known physical mechanisms, identify a strain-induced change of the driving field arising from built-in Schottky junctions at electrodes and suggest a new mechanism of strain-induced charging of tilted domain walls (wall sections). Studying the FE switching under reversible controlled strain states in various FE materials, from macroscopic (FE capacitors) to microscopic (local domain imaging) scale, will advance the fundamental understanding of the domain switching processes.

简介：

郭尔佳，2012年毕业于中国科学院物理研究所，获博士学位，期间获中科院“三好学生”、“朱李月华奖学金”、物理所所长奖等。2012年4月至2014年7月，在德国马丁路德大学（Martin-Luther University Halle-Wittenberg）和莱布尼茨固体材料研究所（IFW Dresden）从事博士后研究，主要探索晶格应力对外延氧化物薄膜的电输运、磁性及铁电性等的影响及其物理机制。同期，于马克斯-普朗克微结构物理研究所（Max-Plank Insitute of Microstructure Physics Halle）做访问学者。2014年8月至今，在德国美因茨大学（Johannes Gutenberg University Mainz）研究氧化物自旋塞贝克效应。目前已在Advanced Materials、Applied Physics Letters、New Journal of Physics等国外重要学术期刊发表SCI论文近40篇。其中，关于应力对铁电畴壁动力学的研究成果被Nature Materials作为亮点报道。

时间：2015年5月13日下午3：30

地点：中科院物理研究所M236会议室

联系人：金奎娟 研究员 （Tel：82648099）

主办单位：中国科学院光物理重点实验室