Field-Modulation Imaging of Ferroelectric Domains in Molecular Single-Crystal Films
Field-Modulation Imaging of Ferroelectric Domains in Molecular Single-Crystal Films
复制标题
分子单晶薄膜中铁电畴的场调制成像
DOI：
10.1103/physrevapplied.11.014046
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发表时间：
2019
影响因子：
4.6
通讯作者：
and T. Hasegawa
中科院分区：
文献类型：
--
作者：
Y. Uemura;S. Arai;J. Tsutsumi;S. Matsuoka;H. Yamada;R. Kumai;S. Horiuchi;A. Sawa;and T. Hasegawa
许多氢键有机铁电体表现出大的自发极化的低场开关。虽然π共轭有机分子的可开关电偶极子解释了大的自发极化，但其相关的光电过程尚未被用于探测铁电性。我们表明，在电光响应的变化，使可视化的铁电畴和畴壁的氢键分子共晶的单晶膜。高灵敏度和快速可视化是通过前向和反向场应用之间的差分光学图像传感来实现的。我们称这种技术为“铁电场调制成像（FFMI）。”独特的光学探测性质揭示了薄膜内存在两种类型的畴壁，表现出不同的三维取向;一种大致垂直于薄膜平面，而另一种相对于平面的法线有相当大的倾斜。我们解释说，这两个域壁是稳定的，以产生实质性的中性被定向平行于极化的方向。本研究为探索铁电材料中畴壁的三维拓扑性质开辟了一条途径。
Many hydrogen-bonded organic ferroelectrics exhibit low-field switching of large spontaneous polarizations. Although the switchable electric dipoles ofπ-conjugated organic molecules account for the large spontaneous polarizations, their relevant optoelectronic processes have not been used to probe the ferroelectricity. We show that the variation in electro-optic response enables visualization of the ferroelectric domains and domain walls in single-crystal films of a hydrogen-bonded molecular cocrystal. Highly sensitive and rapid visualization is realized by difference optical image sensing between the forward and reverse field applications. We call this technique “ferroelectrics field modulation imaging (FFMI).” The unique optical-probe nature reveals the existence of two types of domain walls showing different three-dimensional orientations within the films; one is roughly perpendicular to the film plane, whereas the other is considerably tilted from the normal to the plane. We explain that both of the domain walls are stabilized to generate substantial neutrality by being directed parallel to the direction of polarization. This study opens a route for exploring the three-dimensional topological nature of domain walls in ferroelectric materials.