Ferroic Domain Dynamics by In-Situ Transmission Electron Microscopy Techniques

铁材料通常被用作各种设备的关键部件，例如传感器和执行器，并且特别有希望用于存储器和电阻等设备。铁氧体的关键特征是等效基态的发展，即为最小化系统自由能而形成的域。一般来说，畴出现在材料经历铁性相变之后，其起源是结构剪切（铁弹性）或电偶极矩（铁电性）。畴的可逆切换最终实现了铁的功能。所有的畴都被畴壁（DWs）物理地分开，畴壁的尺寸可以达到纳米级。研究表明，这些界面表现出新的特性，并且是铁材料中的活性元素（而不是本体本身），使它们对纳米电子学特别有吸引力。随着当前器件小型化的趋势，这带来了一个新的研究领域，即领域工程，在这个领域中，铁的功能特性可以通过修改几何形状、应变或电景观来调整。可以从对域和域边界的更全面的理解和控制中直接受益的技术示例是存储设备、光学和声纳探测器。该项目的目标是双重的，a)在微观和纳米尺度上对铁弹性域的域动力学有更深入的了解，作为应用外部刺激（温度和应变）的函数，b)创建新的配置，允许铁弹性域（注入和随后的运动）的确定性控制。后者将涉及创建类似器件的结构，其中应变将通过压电层的偏置引入。压电材料将必要的应变传递给铁弹性试样进行域运动。该项目的实质性部分涉及样品制备技术的发展，特别是聚焦离子束。该项目将使用原位TEM加热和偏置，结合原子力显微镜等其他显微镜技术来成像和探测区域运动。该项目及其目标代表了一个独特的机会来研究铁弹性域的基本方面，以及类似器件的样品，这些样品将为未来的器件，特别是电子应用提供不同的见解。被认为与项目有关的领域；-材料表征-凝聚态物理

Ferroic materials are routinely being used as key components for a wide variety of devices, such as sensors and actuators, and are particularly promising for devices such as memories and resistors. Ferroics' key characteristics are the development of equivalent ground states, known as domains that form to minimise the system's free energy. In general, domains appear after the material undergoes a ferroic phase transition, which have their origins in structural shear (ferroelastics), or electrical dipole moments (ferroelectrics). The reversible switching of domains is what ultimately enables ferroics' functionality.All domains are physically separated by domain walls (DWs) which can have dimensions in the nanoscale regime. It has been shown that these interfaces exhibit novel properties, and are the active element in the ferroic material (instead of the bulk itself), making them especially attractive for nano-electronics. This, along the current trend on device miniaturisation, has brought a new area of research focused on domain engineering, where the functional properties of ferroics can be tuned by modifying the geometry, strain or electrical landscape. Examples of technologies that could directly benefit from a more comprehensive understanding and control over domains and domain boundaries are memory devices and optical and sonar detectors.The aims of this project are two-fold, a) to obtain a deeper understanding of domain dynamics in ferroelastic domains at the micro and nanoscale as a function of applying external stimuli (temperature and strain) and b) to create novel configurations that will allow deterministic control of the ferroelastic domains (injection and subsequent motion). The latter will involve the creation of device-like structures, where strain will be introduced via biasing of a piezoelectric layer. The piezoelectric material will transfer the necessary strain to the ferroelastic sample for domain motion.A substantial part of this project involves the development of sample preparation techniques, especially by Focused ion beam. The project will use in-situ TEM heating and biasing carried out in combination with other microscopy techniques such as atomic force microscopy to image and probe domain motion.This project and its aims, represent a unique opportunity to study fundamental aspects of ferroelastic domains, along with device-like samples that will provide a different insight for future devices, in particular, for electronic applications.Areas considered relevant to the project;- Materials Characterisation- Condensed Matter Physics