Investigating the fabrication and dipole characteristics of complex ferroelectric nanoshapes

铁电体和铁磁体中极化或磁化顺序的传统观点是，局部偶极子或磁矩排列成整齐的行和列，并且整齐排列的组之间的边界必须严格符合主体材料的晶体学（传统的条纹畴）。然而，最近在三维尺寸受限的软铁磁体的实验研究已经揭示了完全不同的磁畴状态的存在，形成涡旋。与铁磁性行为的许多方面一样，铁电体中的电极化行为中的类似性质经常被看到，最近的建模强烈表明，这种涡旋畴状态也应该存在于铁电体中。铁磁体和铁电体之间的能量差异意味着这种不寻常的行为只有在铁电体尺寸减小到约10 nm时才会占主导地位。创建这样的小结构和表征其域状态是一个严重的挑战，实验参与铁电研究，但新的发现的潜力是巨大的。此外，简单的涡旋结构可能只是冰山的尖端，因为已经假设了更多的奇异域模式：例如，一些理论家提出了静电螺线管类似物的可能性。鉴于迄今为止所进行的研究，以及理论家所做的假设，在铁电体中创建三维约束纳米结构，以及随后对其畴特征的分析，显然代表了一个令人兴奋和具有挑战性的问题。该项目将通过将纳米级铁电制造的专业知识与电子全息、二次谐波近场光学、纳米拉曼光谱和扫描探针显微镜等专业表征技术相结合来解决这一研究领域。该计划建立在已经建立的成功合作之间的铁电活动在女王大学贝尔法斯特和剑桥，这是由国际专家在具体选择的表征技术增强。

The traditional view of the ordering of polarisation or magnetisation in both ferroelectrics and ferromagnets is that local dipoles or magnetic moments are arranged into neat rows and columns, and that boundaries between neatly arranged groups must strictly conform to the crystallography of the host material (conventional stripe domains). However, recent experimental research in three-dimensionally size-constrained soft ferromagnets has revealed the existence of completely different domain states which form into vortices. As with many aspects of behaviour in ferromagnetism, analogous properties in the behaviour of the electrical polarisation in ferroelectrics is often seen, and recent modelling strongly suggests that such vortex domain states should also exist in ferroelectrics. Differences in the energetics between ferromagnets and ferroelectrics means that such unusual behaviour is only expected to dominate whenever ferroelectric dimensions are reduced to the order of ~10 nm. The creation of such small structures and the characterisation of their domain states represents a serious challenge to experimentalists involved in ferroelectric research and yet the potential for new discovery is immense. Further, simple vortex structures may only be the tip of the ice-berg, as much more exotic domain patterns have been postulated: for example some theorists have suggested the possibility of an electrostatic solenoid-analogue. Given the research performed to date, and the postulations made by theorists, the creation of three-dimensionally constrained nanostructures in ferroelectrics, and the subsequent analysis of their domain characteristics, clearly represents an exciting and challenging problem. This project will address this area of research by combining expertise in nanoscale ferroelectric fabrication with specialist characterisation techniques such as electron holography, second-harmonic near field optics, nano-Raman spectroscopy and scanning probe microscopy. The programme builds on an already established successful collaboration between ferroelectric activities in Queen's University Belfast and Cambridge, and this is augmented by international experts in specifically chosen characterisation techniques.