The topologically protected vortex–antivortex (V–AV) domain structure in ferroelectric hexagonal manganites has been highly concerned recently, but its stability against intrinsic defects remains to be understood, given the claim that a topological structure would be robust against defects and other perturbations. In fact, it is also known that the V–AV structure is sensitive to the sample quality, and such a well-developed structure is hardly observed in thin films and defective single crystals. In this work, we investigate the influence of anti-trimer point defects on the stability of the V–AV domain structure by employing the phase-field simulation based on the Landau–Devonshire phenomenological theory. It is revealed that the characteristic V–AV structure essentially relies on the anti-trimer point defects under consideration. These defects lower the trimerization transition temperature on one hand and produce pinning effect on the vortex cores/walls on the other hand. However, the V–AV structure does remain robust if the anti-trimer magnitude of these defects is relatively weak but will be eventually destroyed if the anti-trimer magnitude is strong.

中文翻译：

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六方锰矿中反三聚体点缺陷抑制涡旋-反涡旋结构

铁电六方锰酸盐中受拓扑保护的涡旋-反涡旋（V-AV）域结构最近受到高度关注，但考虑到拓扑结构对缺陷和其他扰动具有鲁棒性的说法，其对固有缺陷的稳定性仍有待了解。事实上，众所周知，V-AV结构对样品质量很敏感，在薄膜和有缺陷的单晶中很难观察到这种发达的结构。在这项工作中，我们通过采用基于 Landau-Devonshire 现象学理论的相场模拟来研究反三聚体点缺陷对 V-AV 域结构稳定性的影响。结果表明，特征 V-AV 结构基本上依赖于所考虑的抗三聚体点缺陷。这些缺陷一方面降低了三聚转变温度，另一方面对涡核/壁产生钉扎效应。然而，如果这些缺陷的反三聚体强度相对较弱，则 V-AV 结构确实保持稳健，但如果反三聚体强度较大，则最终会被破坏。