Study of the dynamic properties of magnetic skyrmions using diffractive ferromagnetic resonance

在手性晶格磁体和工程异质结构中发现了磁性天子，即以量子化拓扑不变量为特征的旋涡状自旋织构。由于其新兴的量子特性，它们在外场下的动力学对于基础科学和自旋电子器件中的技术应用都是至关重要的问题。该项目的目的是利用铁磁共振（FMR）和共振弹性软x射线散射（REXS）研究远程有序磁系统及其动力学特性。一个例子是手性晶格磁体Cu2OSeO3中斯基子晶格的三种不同的动力学模式。除了是一个特性良好的模型系统外，这种绝缘的斯基子材料还具有多铁性，导致自旋诱导铁电，具有应用潜力，例如微波二极管。该项目的重点是获得对skyrmions系统的磁化动力学的详细理解，这为skyrmions在快速开关设备中的实际应用铺平了道路。单个斯基米子漩涡的直径约为60纳米。如此小的长度尺度要求高的空间分辨率，因此大多数磁显微镜技术是不合适的。REXS可以用偏振软x射线来表征磁有序，光子能量调谐到Cu L边缘。由于入射x射线的极化性质，REXS对磁化矢量的三个分量具有不同的灵敏度。REXS对于skyrmions的研究具有独特的优势：它具有元素选择性，对磁顺序具有非常高的灵敏度，提供可变采样面积，并允许快速有效的数据采集。另一方面，FMR是研究动态磁性质的有力工具，如共振模式和阻尼特性以及各向异性。这些互补的技术将被应用于研究各种自旋结构的自旋动力学。该项目是与钻石光源，特别是与Gerrit van der Laan教授小组共同努力的结果。工业联系存在通过我们的EPSRC skyrmion拨款与西部数据，日立，IBM，三星和希捷科技。该项目与EPSRC的研究领域“凝聚态物质：磁性和磁性材料”和“自旋电子学”相一致。

Magnetic skyrmions, i.e., vortex-like swirling spin textures characterized by a quantized topological invariant, have been found in chiral-lattice magnets and engineered heterostructures. Their dynamics under external fields is an issue of vital importance for both fundamental science, owing to their emergent quantum properties, and technological applications in spintronic devices owing to their topological protection.The aim of the Project is to use ferromagnetic resonance (FMR) and resonant elastic soft x-ray scattering (REXS) to study long-range ordered magnetic systems and their dynamic properties. One example are the three different dynamical modes of the skyrmion lattice in the chiral-lattice magnet Cu2OSeO3. Apart from being a well-characterised model system, this insulating skyrmion material has also multiferroic properties leading to spin-induced ferroelectricity with an application potential as, e.g., microwave diodes. The Project is focused on gaining understanding of the magnetisation dynamics of skyrmion systems in great detail, which paves the way for the practical use of skyrmions in fast-switching devices. An individual skyrmion vortex has the diameter of around 60 nm. Such a small length scale requires high spatial resolution, therefore most of the magnetic microscopy techniques are unsuitable. REXS can be used to characterise the magnetic ordering by using polarized soft x-rays with the photon energy tuned to the Cu L edge. Due to the polarized nature of the incidence x-rays, REXS has different sensitivities to the three components of the magnetization vector. REXS has unique advantages for the study of skyrmions: it is element-selective, has a very high sensitivity for magnetic order, provides a variable sampling area, and allows for fast and efficient data acquisition. FMR, on the other hand, is a powerful tool for the study of dynamic magnetic properties such as the resonance modes and damping characteristics, as well as anisotropies. These complementary techniques will be applied to study the spin dynamics of various spin structures. This project is a joint effort with the Diamond Light Source, and in particular with the group of Prof Gerrit van der Laan. Industrial contacts exist via our EPSRC skyrmion grant with Western Digital, Hitachi, IBM, Samsung, and Seagate Technology.This project aligns with EPSRC's research areas "Condensed Matter: Magnetism and Magnetic Materials" and "Spintronics".