论文标题

通过第二次谐波生成光谱成像描述复杂的铁电域结构

Delineating complex ferroelectric domain structures via second harmonic generation spectral imaging

论文作者

Li, Wei, Ma, Yunpeng, Feng, Tianyi, Kalinin, Sergei V., Li, Jing-Feng, Li, Qian

论文摘要

了解铁电材料中晶体学对称性破坏的机制和空间相关性对于调整其功能特性至关重要。尽管长期以来在铁电研究中使用了光学第二次谐波生成(SHG),但其探测复杂极性材料的能力尚未完全实现。在这里,我们开发了一种在家庭设计的激光扫描SHG显微镜上实现的SHG光谱成像方法,并演示了其用于(K,NA)NBO3单晶模型系统的应用。监督模型拟合分析可产生有关组成域变体的极化矢量方向和相对部分的全面信息,以及它们在整个多态相变的中的热演化。我们观察到在低温下正骨相的意外持久性,指向阶段竞争。此外,我们表明,无监督的矩阵分解分析可以快速而忠实地揭示域配置,而无需先验有关特定材料系统的知识。 SHG光谱成像方法可以很容易地扩展到其他具有潜力的铁电材料,以进一步增强。

Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties. While optical second harmonic generation (SHG) has long been utilized in ferroelectric studies, its capability for probing complex polar materials has yet to be fully realized. Here, we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope, and demonstrate its application for a model system of (K,Na)NbO3 single crystals. Supervised model fitting analysis produces comprehensive information about the polarization vector orientations and relative fractions of constituent domain variants as well as their thermal evolution across the polymorphic phase transitions. We observe an unexpected persistence of the orthorhombic phase at low temperatures, pointing to the phase competitions. Besides, we show that unsupervised matrix decomposition analysis can quickly and faithfully reveal domain configurations without a priori knowledge about specific material systems. The SHG spectral imaging method can be readily extended to other ferroelectric materials with potentials to be further enhanced.

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