Observing, Creating and Addressing Topological Spin Textures in a Monolayer XY Magnet

在20世纪70年代早期的一系列开创性工作中，约翰·科斯特里茨和大卫·斯伯莱斯首先将拓扑学的概念与固体物理学联系起来。这个框架的基础是离散的拓扑单元，一个物体定义为它的阻力被平滑变形成一个连续的背景，在这种方式下，一个磁盘不能平滑变形成一个环或环面。Kosterlitz和Kosterless指出，他们所探索的系统的最有利构型必须包含这些拓扑单元。然后，他们继续预测基于这些物体的材料相变没有对称性破缺，违反了当时所有已知的理论和观察。这种所谓的拓扑相变随后被用来描述薄膜超导体、液晶和二维磁体中的相变。由于这项工作，Kosterlitz和Kosterless分享了2016年诺贝尔奖。然而，尽管这些发现具有开创性的性质，并且随后得到了广泛的实验支持，但最初预测的拓扑单元从未在单个单元水平上被观察到。在这项工作计划中，我们将使用高度先进的显微镜技术，首次“看到”这些拓扑对象中的每一个。这些显微镜无与伦比的分辨率可以进一步用于映射物体的内部，一直到它们的原子构建块。这些实验，当与先进的计算方法相结合，以解决Kosterlitz和Wendless所考虑的原始问题时，将为这些拓扑保护对象提供一个全新的微观画像。然而，这项工作的目的远远超出了简单地观察拓扑单元;我们将开发和提供一系列方法来主动操纵这些对象。第一套操作技术将利用显微镜本身的影响，就像放大镜可以用来点火一样。第二个系列的方法将修改周围的环境，以影响拓扑对象的属性和行为。由于单个拓扑单元不能平滑变形，因此它代表了信息技术的一个前所未有的机会：使用拓扑状态来存储和保护一段信息。拓扑保护的数据避开了传统的基于能量的方法来保护信息，使它们非常有希望成为高密度，节能的磁信息技术方法。最终，提出的一组实验旨在告知我们如何从微观拓扑元素走向计算机的全功能单元。沿着获得的见解将回答许多更基本的问题：拓扑在多大程度上保护信息？这些单元在真实的，即有缺陷的材料中表现如何？我们可以采取什么方法来影响这些物体的基本行为？

In a series of pioneering works in the early 1970's, John Kosterlitz and David Thouless first connected the concept of topology to the physics of solids. The basis of this framework is the discrete topological unit, an object defined by its resistance to being smoothly deformed into a continuous background, in the way a disk cannot be smoothly deformed into a ring or torus. Kosterlitz and Thouless showed that the most favourable configurations of the systems they explored must host these topological units. They then went on to predict a material phase transition without symmetry breaking based on these objects, violating all known theories and observations at the time. This so-called topological phase transition has subsequently been used to describe transitions in thin-film superconductors, liquid crystals, and two-dimensional magnets. For this work, Kosterlitz and Thouless shared the 2016 Nobel Prize. Yet, despite the groundbreaking nature of these findings and their subsequent wide-ranging experimental support, the topological units originally predicted have never been observed at the single unit level. In this programme of work, we will use highly advanced microscopy techniques to "see" each of these topological objects for the first time. The unparalleled resolution of these microscopes can be further used to map the interior of the objects all the way down to their atomic building blocks. These experiments, when combined with advanced computational approaches to the original problem considered by Kosterlitz and Thouless, will provide an entirely new microscopic portrait of these topologically protected objects.Yet, this work aims far beyond simply observing the topological units; we will develop and deliver a series of approaches to actively manipulate these objects. The first set of techniques for manipulation will utilize influence from the microscope itself, in much the same way a magnifying glass can be used to start a fire. The second series of approaches will modify the surrounding environment to influence the properties and behaviour of the topological objects. As an individual topological unit cannot be smoothly deformed, it represents an unprecedented opportunity for information technology: using a topological state to store and protect a piece of information. Topologically protected data sidesteps the conventional approaches based on energy to protect information, making them extremely promising for high-density, energy efficient approaches to magnetic information technologies.Ultimately, the set of experiments proposed is designed to inform how we might move from a microscopic topological element toward a fully functional unit of a computer. The insights picked up along the way will answer many more fundamental questions: To what extent does topology protect information? How do these units behave in real, that is defective, materials? What approaches can we take to influence the fundamental behaviour of these objects?