Detection and Manipulation of Magnetic Skyrmion Domains in Silicide and Germanide Nanowires for Spintronic Applications

本计画旨在利用矽化物及锗化物奈米线之手性磁性Skyrmion畴，以应用于磁性资料储存。Skyrmions是一种新型的奇异磁有序，其中电子自旋定向形成拓扑非平凡的类水池结构。它们最近在非中心对称的B20单硅化物（MnSi，Fe 1-xCoxSi）或单锗化物（FeGe）中被发现。Skyrmions可以被认为是磁结，准粒子状的域，在磁场和温度的小扰动下是稳定的，并且不会强烈地钉扎到晶格或杂质。由于自旋力矩相互作用，Skyrmion强烈耦合到电流，因此需要低得多的临界电流密度来驱动Skyrmion畴的运动。Skyrmions为实现自旋电子和磁存储器件设计提供了新的机会。 此外，纳米线提出了一个理想的系统来实现，检测和操纵孤立的手性磁性Skyrmion在没有外加磁场的情况下，由于稳定的Skyrmion相在受限的一维几何形状。 基于他们在金属硅化物和锗化物纳米线生长方面的进展以及使用纳米线构建块进行自旋电子器件研究的专业知识，PI计划观察，测量和操纵非中心对称B20硅化物纳米线中的手性Skyrmions，如Fe 1-xCoxSi和MnSi。具体来说，通过与东京大学的国际合作，洛伦兹透射电子显微镜将用于可视化这些纳米线中的Skyrmions。此外，由于Skyrmions拓扑霍尔效应将在纳米线电测量。最后，我们将探讨奈米电子元件中Skyrmions的涌现动力学及其运动。智力价值：该研究项目通过将现有的纳米线材料与仔细的设备和物理研究相结合，首次提供了观察和电学检测Skyrmion运动的机会。纳米线的几何形状有几个优点，薄膜和散装样品，更适合于证明这种新的现象，因此纳米线可以作为一个模型材料平台，需要从基础物理研究Skyrmions和更多的应用设备的工作和最终的应用。由于其独特的和上级的性能，Skyrmions具有优于传统的金属铁磁体畴壁。在纳米线中实现和电检测基态隔离Skyrmions将证明利用Skyrmions进行磁存储的概念验证。该项目的更广泛影响包括，该项目的成功将为低功耗，增强性能和大容量数据存储的磁存储器和自旋电子器件开辟新的设计概念，从而带来广泛的技术影响。教育和推广是紧密结合在这个项目中的积极研究，招募代表性不足的本科生参加纳米技术研究的自旋电子材料和设备，并进一步发展为高中学生和教师的纳米技术研讨会。在工作坊期间，学生将研究二手电脑硬盘和集成电路芯片，让学生学习自旋电子学和纳米电子学的基本概念，以及它们如何连接到数字小工具，从而激发他们对科学和工程的兴趣。

This project seeks to utilize chiral magnetic Skyrmion domains in nanowires of silicides and germanides for magnetic data storage applications. Skyrmions are a novel type of exotic magnetic ordering in which electron spins orient to form a topologically non-trivial whirlpool-like structure. They were recently discovered in non-centrosymmetric B20 monosilicides (MnSi, Fe1-xCoxSi) or monogermanide (FeGe). Skyrmions can be thought of as magnetic knots, quasi-particle-like domains that are stable to small perturbations in magnetic field and temperature and do not pin strongly to the crystal lattice or impurities. Skyrmions strongly couple to electrical currents due to the spin torque interaction therefore much lower critical current density is needed to drive the motion of Skyrmion domains. Skyrmions present novel opportunities for implementing spintronic and magnetic storage device designs. Furthermore, nanowires present an ideal system to realize, detect, and manipulate isolated chiral magnetic Skyrmions in the absence of an applied magnetic field due to the stabilization of the Skyrmion phase in confined one-dimensional geometry. Building on their progress in the growth of metal silicide and germanide nanowires and the expertise in spintronic device investigations using nanowire building blocks,PI plan to observe, measure, and manipulate chiral Skyrmions in nanowires of non-centrosymmetric B20 silicides, such as Fe1-xCoxSi and MnSi. Specifically, through an international collaboration with the University of Tokyo, Lorentz transmission electron microscopy will be used to visualize Skyrmions in these nanowires. Furthermore, topological Hall effect due to Skyrmions will be electrically measured in nanowires. Finally, the emergent dynamics of Skyrmions and their motions will be investigated in nanowire electrical devices. The intellectual merit: This research project presents the first opportunity for observing and electrically detecting Skyrmion motion by integrating existing nanowire materials with careful device and physical studies. Nanowire geometry has several advantages over thin film and bulk samples and is better suited for demonstrating such novel phenomenon therefore nanowires can serve as a model material platform that takes the study of Skyrmions from the fundamental physics and to more applied device work and eventual applications. Due to their unique and superior properties, Skyrmions have advantages over the conventional domain walls in metallic ferromagnets. The realization and electrical detection of ground state isolated Skyrmions in nanowires would demonstrate the proof-of-concept for utilizing Skyrmions for magnetic storage. The broader impact of the project includes that the success of the project will open up new design concepts for magnetic memory and spintronic devices with low-power, enhanced performance, and mass data storage, therefore bringing broad technological impacts. Education and outreach is closely integrated with active research in this project by recruiting underrepresented undergraduate students to participate in nanotechnology research in spintronic materials and devices, and by further developing a nanotechnology workshop for high school students and teachers. Used computer hard drives and integrated circuit chips will be examined during the workshop to allow students to learn basic concepts in spintronics and nanoelectrics and how they connect to digital gadgets, encouraging their interest in science and engineering.