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由于铁电材料的畴取向及所占比例直接与铁电器件运行时的畴翻转过程及稳定性相关联，使得铁电材料畴分布成为了一个令人心驰神往的课题，并吸引了研究者的关注。
为精准确定铁电材料的畴分布情况，来自湘潭大学的钟向丽和周益春教授，及国防科技大学的袁建民教授领导的团队，开发了铁电畴分布表征的新方法：方位角-偏振依赖光学二次谐波探测方法。他们收集了不同样品方位角和入射光偏振角下铁电薄膜产生的光学二次谐波信号，并建立了相关的方位角-偏振依赖光学二次谐波模型；通过结合测得的相关实验数据与理论模型，确定了71°和109°畴壁的菱方相BiFeO3，及四方相BiFeO3、Pb(Zr0.2Ti0.8)O3和BaTiO3等铁电薄膜复杂或简单的畴结构，并准确获得了该畴结构的分布情况。此项工作开发了一种优化的全光学方法，能准确得到铁电薄膜中的铁电畴结构及分布情况，可用来跟踪和评估铁电器件中铁电畴的演变过程。
该文近期发表于npj Computational Materials 4: 39 (2018)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Characterization of domain distributions by second harmonic generation in ferroelectrics
Yuan Zhang, Yi Zhang, Quan Guo, Xiangli Zhong, Yinghao Chu, Haidong Lu, Gaokuo Zhong, Jie Jiang, Congbing Tan, Min Liao, Zhihui Lu, Dongwen Zhang, Jinbin Wang, Jianmin Yuan & Yichun Zhou
Domain orientations and their volume ratios in ferroelectrics are recognized as a compelling topic recently for domain switching dynamics and domain stability in devices application. Here, an optimized second harmonic generation method has been explored for ferroelectric domain characterization. Combing a unique theoretical model with azimuth-polarization-dependent second harmonic generation response, the complex domain components and their distributions can be rigidly determined in ferroelectric thin films. Using the proposed model, the domain structures of rhombohedral BiFeO3 films with 71° and 109° domain wall, and, tetragonal BiFeO3, Pb(Zr0.2Ti0.8)O3, and BaTiO3 ferroelectric thin films are analyzed and the corresponding polarization variants are determined. This work could provide a powerful and all-optical method to track and evaluate the evolution of ferroelectric domains in the ferroelectric-based devices.
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