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

非技术描述：研究铁电体的电子行为是一个重要而具有挑战性的科学问题，它关系到复杂氧化物材料的基本物理性质。本研究的一个特别有前途的方面是具有约束几何的低维铁电结构在外电场下的动力学行为。对于绝大多数应用来说，域结构的切换和相关的演变是设备功能的基石。本研究将回答有关纳米级铁电结构中极化反转的复杂几何、尺寸和动力学之间相互作用的问题，以及基于铁电的器件（如高密度非易失性存储器和数据存储器件、自旋滤波器和微波器件）的基本缩放限制。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良好协调的合作研究。英国部分的工作由工程和物理科学研究委员会（EPSRC）支持。特别是从代表性不足的群体中招收的学生，通过丰富他们的专业准备和教育经验，从接触国际研究中受益。技术细节：该项目正在调查和寻求理解减小尺寸和增加形态复杂性影响中、纳米级铁电体开关行为的方式。实验方法包括制造独立的单晶纳米板、纳米棒和模型铁电BaTiO3的纳米点，并通过先进的频闪压响应力显微镜（S-PFM）方法表征其动态开关行为。样品正在使用聚焦离子束（FIB）技术制备，然后在英国贝尔法斯特女王大学（QUB）的John Martin Gregg教授小组中进行结构表征。先前的研究已经证明，FIB制造模式对铁电体在缩小尺度上的基本行为提供了特别清晰的见解。S-PFM被用于绘制共面电极间外加电场诱导的面内开关过程中畴壁运动的动力学。光纤工程缺陷在薄铁电板，如孔，缺口和狭缝，允许直接研究的方式，物理缺陷改变区壁的成核和传播。该项目的结果将导致在理解电和机械边界条件和样品缩放对铁电开关基本机制的作用方面取得根本性进展。

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.