Topological defects such as vortices in ferroelectric materials are attracting tremendous interest because of their splendid possibilities for unique physical phenomena and potential applications in nanoelectronic devices. However, reports of the vortex structure have been scarce in organic ferroelectrics, which are highly desirable for their mechanical flexibility, easy and environment-friendly processing, and low acoustical impedance. Here, we successfully observed the robust triangular domains in a single-component organic ferroelectric, 2-(hydroxymethyl)-2-nitro-1,3-propanediol (1), six of which can form a six-fold vertex domain structure. To our knowledge, it is the first time that such an intriguing topological vortex gets experimentally confirmed in ferroelectrics. Moreover, the symmetry change of 1 with an Aizu notation of m3mF1 leads to the most 48 crystallographically equivalent polarization directions among all ferroelectrics. With those benefits and excellent piezoelectric properties, compound 1 shows great potential as a reconfigurable electronic element or a mechanical sensor for soft robotics, flexible and wearable devices, and bio-machines.

中文翻译：

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具有最等效极化方向的单组分有机铁电体中的六重顶点

铁电材料中的涡旋等拓扑缺陷引起了极大的兴趣，因为它们在纳米电子器件中具有独特的物理现象和潜在应用的可能性。然而，有机铁电体中涡旋结构的报道很少，有机铁电体因其机械柔韧性、易于环保的加工以及低声阻抗而备受青睐。在这里，我们成功地观察到单组分有机铁电体 2-(羟甲基)-2-硝基-1,3-丙二醇 (1) 中的稳健三角形域，其中六个可以形成六重顶点域结构。据我们所知，这是第一次在铁电体中通过实验证实这种有趣的拓扑涡旋。而且，具有 m3mF1 的会津符号的 1 的对称性变化导致所有铁电体中最多 48 个晶体学等效极化方向。凭借这些优点和优异的压电性能，化合物 1 作为可重构电子元件或软机器人、柔性和可穿戴设备以及生物机器的机械传感器显示出巨大的潜力。