Imaging skyrmions in synthetic antiferromagnetic multilayers

Skyrmions是磁性材料中的圆形磁畴/磁畴壁，近年来引起了人们对自旋电子应用的极大兴趣。根据材料的性质，天狼星具有一种被称为拓扑保护的属性，这意味着当它们相互作用时，它们很难被湮灭。此外，当它们在磁性层之间具有反铁磁耦合的多层膜中形成时，它们没有天际霍尔角，所以当使用自旋极化电流来移动它们时，它们沿着电荷流动的方向移动，没有偏差。天球的大小在很大程度上取决于多层膜的组成和厚度等。在这个项目中，我们将研究不同材料体系中的天球。这些材料将通过透射式电子显微镜(TEM)的方法进行表征，其磁性结构由洛伦兹成像模式成像。电影的沉积将在利兹大学进行，表征将在格拉斯哥大学进行。研究的是尺寸小于100 nm的Skymrion，在连续薄膜系统中，Skyrmions倾向于在某一成核场的任意位置形成。使用不同的方法，我们的目标是使特定位置的单个孤立的Skyrmions成核。这是通过局域化的纳米结构缺陷和操纵表面位置的磁各向异性来提出的。原位成像将揭示特定位置的Skyrmions成核是可能的。我们还将探索然后移动带有自旋极化电流的Skyrmions，以演示设备应用的可能性。除了瞬变电磁法的工作外，还将进行光束线实验，以补充瞬变电磁法成像。该项目还涉及与国家物理实验室的同事合作，他们也对通过扫描探针显微镜进行成像感兴趣。该项目与EPSRC在研究用于自旋电子学应用的新型和先进材料系统方面的优先事项一致。例如，这个材料系统是一个复杂的多层膜，具有磁层和非磁层，具有3种不同的磁交换相互作用，为天空离子的稳定提供了合适的环境。原则上，精确到几十纳米的Skyrmions可以为动态设备提供可控制的移动磁位，但不需要机械移动部件。这可以实现为逻辑设备或存储器存储。

Skyrmions are circular magnetic domains/domain walls in magnetic materials and have attracted great interest recently for spintronic applications. By the nature of the materials the skymrions possess a property known as topological protection, which means that they are hard to annihilate when they interact. Additionally when they are formed in multilayer films with antiferromagnetic coupling between the magnetic layers they have no skyrmion Hall angle, so when a spin polarised current is used to move them they move with the direction of charge flow without deviation. The size of the skymrions depend crucially on the multilayer composition in terms of layer composition and thickness etc. In this project skyrmions in different materials systems will be studied. The materials will be characterised by the methods of transmission electron microscopy (TEM) with the magnetic structure imaged by Lorentz imaging modes. Deposition of films will be carried out at the University of Leeds and the characterisation will be performed at the University of Glasgow. Skymrions with sizes less than 100 nm are to be studied.In a continuous thin film system skyrmions tend to form at random positions at a certain nucleation field. Using various approaches we aim to nucleate site specific single isolated skyrmions. This is proposed via localised nanostructured defects and manipulation of the magnetic anisotropy at surface sites. In situ imaging will reveal that site specific nucleation of skyrmions is possible. We will also explore then moving the skyrmions with spin polarised currents to demonstrate possibilities for device application. In addition to TEM work beamline experiments will also be carried out to complement the TEM imaging. The project also involves working with colleagues at the National Physical Laboratory who are also interested in imaging via scanning probe microscopy.This project aligns with EPSRC priorities in investigating new and advanced materials systems for spintronics applications. For example this materials system is a complex multilayer with magnetic and non magnetic layers possessing 3 different magnetic exchange interactions to provide the right environment for skyrmion stabilisation. In principle skyrmions down to a few 10s of nanometres can provide dynamic devices with controllable moving magnetic "bits", but without mechanical moving parts. This could be implemented logic devices or memory storage.