Anisotropic, meandering domain microstructure in the improper ferroelectric CsNbW2O9
Anisotropic, meandering domain microstructure in the improper ferroelectric CsNbW2O9
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DOI：
10.1063/5.0026040
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发表时间：
2020-10
期刊：
影响因子：
6.1
通讯作者：
S. McCartan;P. Turner;J. A. McNulty;J. R. Maguire;C. J. McCluskey;F. Morrison;J. Gregg;I. MacLaren
中科院分区：
文献类型：
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作者：
S. McCartan;P. Turner;J. A. McNulty;J. R. Maguire;C. J. McCluskey;F. Morrison;J. Gregg;I. MacLaren
不适当的铁电材料CsNbW2O9最近被认为是第一个在锰氧化物家族之外表现出类似于稀土锰氧化物带电磁畴壁上增强和减弱电导的六重弯曲磁畴结构的材料。虽然目前还没有证据表明CsNbW2O9中的畴壁电导相对于块体的变化，但微观结构上的相似性强烈地表明这种材料中存在带电的畴壁。在此，我们用压电响应力显微镜和透射电子显微镜对CsNbW2O9的磁畴结构进行了综合研究，揭示了这两个系统的磁畴结构实际上存在着明显的区别。CsNbW2O9的晶体结构引起的限制，即BO6多面体的连通性和纯粹沿c轴发生的原子位移，意味着畴壁优先平行于c方向(材料的极轴)运行，因此保持不带电。使人联想到锰氧化物的特征三叶草结构仍然存在；然而，该结构主要在ab平面上弯曲，因此，根据从其观察的投影方向，看起来不同。由于这种微观结构的限制，带电磁区壁在这种材料中并不普遍。
The improper ferroelectric CsNbW2O9 has recently been highlighted as the first material outside the manganite family to exhibit a similar meandering, sixfold domain structure to that responsible for enhanced and diminished conduction at charged domain walls in the rare earth manganites. While there is no current evidence for variation in domain wall conduction relative to bulk in CsNbW2O9, the similarities in microstructure strongly suggest that charged domain walls are present in this material. Herein, we report a comprehensive study of the domain microstructure of CsNbW2O9 by both piezoresponse force microscopy and transmission electron microscopy to reveal that there are, in fact, clear distinctions in the domain structure of the two systems. Constraints arising from the crystal structure of CsNbW2O9, namely, the connectivity of the BO6 polyhedra and atomic displacements occurring purely along the c axis, mean that domain walls preferentially run parallel to the c direction (the polar axis of the material) and thus remain uncharged. The characteristic cloverleaf domain structure reminiscent of the manganites is still present; however, the structure meanders predominantly in the ab plane and, therefore, appears differently depending on the projection direction from which it is viewed. As a result of this microstructural constraint, charged domain walls are not prevalent in this material.