Spectroscopic Detection of Magnetic Scattering and Quasiparticles at Atomic Resolution in the Electron Microscope

使科学和技术发生革命性变化的半导体设备是基于控制纳米材料中电子电荷传输的能力。然而，作为逻辑器件的组成部分的晶体管的小型化正达到瓶颈，电荷传输的速度正达到其物理极限，突显出对新器件设计的需要。电子设备中使用的电子携带着一条额外的信息，称为自旋。所谓的自旋电子设备除了利用电子自旋的电荷外，还利用电子自旋来更快、更有效地传输信息。因此，它们有可能克服传统电子学的局限性。实现这一概念的一种方法是通过在自旋电子材料中创建“信息波”，即在器件内传播的电荷载流子自旋的周期性振荡。这些自旋波也被称为‘磁振子’。为了有效地在新的电子设备中使用这些磁子，必须可视化并了解它们是如何在自旋电子器件中通过接口或触点产生和传输的，从而阐明如何有效地携带信息。到目前为止，还没有实验工具或方法在相关的纳米甚至原子尺度上提供这种信息。在过去十年中，电子显微镜领域具有决定性的技术和方法的发展使当前产生的仪器的能量分辨率达到了低于5 meV的水平，同时保持了原子尺度的空间分辨率。这种突破性的能力应该能够检测到在激发磁子时观察到的分散在样品中的电子探测器造成的能量损失，这些磁子位于这个MEV能量范围内。因此，这个国际中心到中心合作项目组建了一个团队，他们的研究和专业知识处于扫描透射式电子显微镜(STEM)和电子能量损失光谱(EELS)的前沿，在产生先进电子显微镜和电子散射建模领域的知识、工具和方法方面具有丰富的经验，以期在电子显微镜中展示磁振鳗光谱学。该项目旨在开发实验和理论工具，使我们能够利用基于电子的光谱学在纳米和原子尺度上探测和可视化磁子。一个主要目标是明确地对自旋电子应用材料中磁子的光谱特征进行指纹识别，并将这一观察结果与分析电子显微镜可以提供的丰富结构和化学信息联系起来。最先进的计算工具将使我们能够指导和设计实验参数，并使实验结果合理化。这个项目将提供一种新的方法来研究固体中磁有序和自旋波激发的基本原理，并将提供材料和器件的磁性和电学性质的完整图景。

Semiconductor devices that have revolutionised science and technology are based on the ability to control the transport of electron charges in nanoscale-sized materials. However, the miniaturisation of transistors, the building blocks of logic devices, is reaching a bottleneck and the speed of charge transport is reaching its physical limits, highlighting the need for new device designs. Electrons being used in electronic devices carry an additional piece of information called spin. So-called spintronic devices exploit this electron spin, in addition to its charge, to transport information more quickly and effectively. As a result, they have the potential to overcome the limitations of conventional electronics. A way to implement this concept is through the creation in spintronic materials of 'information waves', periodic oscillations of the spin of charge carriers, which propagate within the devices. These spin waves are also called 'magnons'. In order to effectively use these magnons in new electronics, it is essential to visualise and understand how they are generated and transferred within spintronic devices across interfaces or contacts and thus shed light on how effectively information can be carried. Up to now, no experimental tool or method has been available to provide this information at the relevant nano- or even atomic scale.Era-defining technological and methodological developments in the last decade in the field of electron microscopy have seen the energy resolution of current-generation instruments reach the sub-5meV level while retaining atomic-scale spatial resolution. Such ground-breaking capabilities should enable the detection of energy losses incurred by electron probes scattered within samples being observed when exciting magnons, which lie in this meV energy range. This International Centre-to-Centre Collaborative project thus assembles a team whose research and expertise are at the forefront of scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS), with extensive experience in generating knowledge, tools, and methodologies in the fields of advanced electron microscopy and modelling of electron scattering, with a view to demonstrate magnon EEL spectroscopy in the electron microscope.The project aims to develop the experimental and theoretical tools that will allow us to detect and visualise magnons at the nano and atomic scale with electron-based spectroscopy. A main goal is to fingerprint unambiguously the spectroscopic signature of magnons in materials for spintronic applications and to correlate this observation with the wealth of structural and chemical information that analytical electron microscopy can provide. State-of-the-art computational tools will allow us to guide and design experimental parameters and to rationalised experimental results. This project will provide a new way of studying the fundamentals of magnetic ordering and spin wave excitations in the solid state and it will provide a complete picture of magnetic and electronic properties of materials and devices.