Materials World Network: Critical Scaling of Domain Dynamics in Ferroelectric Nanostructures

非技术描述：研究铁电材料的电子行为是与复杂氧化物材料的基本物理性质有关的重要和具有挑战性的科学问题。这项研究的一个特别有希望的方面是具有约束几何的低维铁电结构在外电场中的动力学行为。对于绝大多数应用来说，域结构的切换和相关演变是设备功能的基石。这项研究将回答有关纳米铁电结构中复杂的几何、尺寸和极化反转动力学与铁电器件的基本比例限制之间的相互作用的问题，这些器件包括高密度非易失性存储器和数据存储器件、自旋过滤器和微波器件。国际学生交换是该项目的重要组成部分，有助于美国和欧洲合作伙伴之间协调良好的合作研究。英国部分的工作得到了工程和物理科学研究理事会(EPSRC)的支持。特别是从代表性不足的群体中招募的学生，通过丰富他们的专业准备和教育经验，正在受益于接触国际研究。技术细节：该项目正在研究和试图了解尺寸减小和形态复杂性增加对介观和纳米尺度铁电材料开关行为的影响方式。该实验方法包括制备独立的单晶纳米片、纳米棒和纳米点模型铁电BaTiO_3，并利用先进的频闪压电式响应力显微镜(S-PFM)方法表征其动态开关行为。这些样品是用聚焦离子束(FIB)技术制备的，然后在英国贝尔法斯特女王大学(QUB)由John Martin Gregg教授团队进行结构表征。先前的研究已经证明，FIB制造模式特别清楚地洞察了铁电材料在缩小尺度下的基本行为。S-PFM被用来绘制平面内转换过程中由共面电极之间施加的外部电场引起的磁畴壁运动的动力学图。薄铁电板中的纤维工程缺陷，如孔洞、凹槽和缝隙，允许直接研究物理缺陷改变磁区壁成核和扩展的方式。该项目的成果将在理解电气和机械边界条件的作用以及样品比例对铁电开关的基本机制的作用方面取得根本性的进展。

NON-TECHNICAL DESCRIPTION: Research into electronic behavior of ferroelectrics is an important and challenging scientific problem related to fundamental physical properties of complex oxide materials. One of the particularly promising aspects of this research is the dynamic behavior of low-dimensional ferroelectric structures with constrained geometry in the external electric field. For the vast majority of applications, it is the switching and the associated evolution of domain structure that is the cornerstone for device functionality. This research will answer questions related to interplay between complex geometry, size and dynamics of polarization reversal in nanoscale ferroelectric structures and the fundamental scaling limits to ferroelectric-based devices, such as high-density non-volatile memory and data storage devices, spin filters and microwave devices. International student exchange is an essential component of the project contributing to the well-coordinated collaborative research between US and European partners. The UK portion of the work is supported by the Engineering and Physical Sciences Research Council (EPSRC). Students recruited into this project from underrepresented groups, in particular, are benefiting from exposure to international research through the enrichment of their professional preparation and education experience. TECHNICAL DETAILS: This project is investigating and seeking to understand the manner in which reduced size and increased morphological complexity affect the switching behavior of meso- and nanoscale ferroelectrics. The experimental approach involves fabrication of free-standing single-crystalline nanoplates, nanorods and nanodots of a model ferroelectric BaTiO3 and characterization of its dynamic switching behavior by means of an advanced 'stroboscopic' Piezoresponse Force Microscopy (S-PFM) method. The samples are being prepared using a Focused Ion Beam (FIB) technique and then structurally characterized at Queen's University Belfast (QUB), UK, in the group of Prof. John Martin Gregg. Prior research has demonstrated that the FIB mode of fabrication gives particularly clear insight into the fundamental behaviour of ferroelectrics at reduced scales. S-PFM is being used to map the dynamics of domain wall motion during in-plane switching, induced by an external electric field applied between coplanar electrodes. FIB-engineered defects in the thin ferroelectric slabs, such as holes, notches and slits, allow direct studies of the manner in which physical defects alter the nucleation and propagation of domain walls. The outcome of the project will lead to fundamental advances in understanding the role of electrical and mechanical boundary conditions and sample scaling on the basic mechanisms of ferroelectric switching.