Creation, Detection, and Manipulation of Isolated Magnetic Skyrmions in Nanowires for Magnetic Storage Applications

本项目旨在研究非中心对称金属硅化物和锗化物纳米线中孤立的磁性天子，用于磁数据存储应用。Skyrmions是一种新型的磁有序构型，其中电子的自旋排列成漩涡状结构。由于它们的纳米尺度可以实现高信息存储密度和超低能耗能力，它们有望成为下一代磁信息存储。纳米线是Skyrmions的理想宿主，因为它们不仅是磁性设备的天然平台，而且还有可能稳定Skyrmions。在初步结果中，PI的小组显示了硅化物和锗纳米线中Skyrmions的稳定性、电学检测和电流驱动动力学的增强，并建议制造新的器件来创建、操纵和检测纳米线中孤立的磁性Skyrmion。这些研究的成功将证明基于Skyrmion的磁存储器件的可行性，并为开发低功耗和高性能的新型自旋电子器件开辟新的设计理念，从而带来广泛的技术影响。未被充分代表的本科生将被招募参加纳米技术研究。有关纳米技术的展览和实践活动将在一年一度的威斯康星工程博览会和麦迪逊科学博物馆开展和进行，以激发公众对科学和工程的好奇心和兴趣。该项目寻求在非中心对称的B20硅化物和锗化物纳米线中利用孤立的磁性天线子用于磁数据存储应用。Skyrmions是一种新型的奇特磁序，其中电子的自旋排列成漩涡状结构。由于在拓扑上非平凡的自旋涡旋排列，Skyrmions可以被认为是自由粒子状的孤立磁畴(即Skyrmion晶格外的Skyrmions)，在磁场和温度的微小扰动下是稳定的，并且不强烈地钉住晶格或杂质。驱动天空微子运动所需的临界电流密度要低得多，因此，它们有望成为下一代磁存储设备，如磁性跑道存储器件，因为它们的纳米尺度可以实现高信息存储密度，而它们的电流驱动运动的低阈值可以实现超低的能量消耗。对于磁性赛道存储设备，Skyrmions由于其稳定性和易于在电流下操作而优于铁磁域。纳米线是Skyrmions的理想宿主，因为它们不仅是磁性赛道存储设备的天然平台，而且还可以潜在地稳定Skyrmions。基于对MNSI和其他B20硅化物单晶纳米线的初步结果，Pi提出了新的器件实验，通过使用洛伦茨透射显微镜、悬臂梁磁测量和霍尔效应测量来创建、操纵和检测纳米线中孤立的磁性天米子，以绘制纳米线中的天米子相图；使用新的磁阻测量来电探测受限天米子；使用完全电学的方法使孤立天子成核；并最终展示了天米子轨道存储器件的原型。这一创新的跨学科项目将已经开发的纳米线材料与仔细的器件研究相结合，以实现第一次实验演示纳米线中Skyrmions的成核，以及可能的基于Skyrmions的概念验证磁道存储设备。

This project seeks to study isolated magnetic skyrmions in nanowires of non-centrosymmetric metal silicides and germanides for magnetic data storage applications. Skyrmions are a novel magnetic ordering configuration in which electron's spins are arranged in whirlpool-like structures. They hold promise for next-generation magnetic information storage because of their nanoscale dimensions that can enable high information storage density and ability for ultralow energy consumption. Nanowires are ideal hosts for skyrmions since they not only serve as a natural platform for magnetic devices but can also potentially stabilize skyrmions. In preliminary results, the PI's group has shown enhanced stability, electrical detection, and current-driven dynamics of skyrmions in silicides and germanides nanowires, and proposes to fabricate novel device to create, manipulate, and detect isolated magnetic skyrmions in nanowires. The success of these studies will demonstrate the feasibility for skyrmion-based magnetic memory devices and open up new design concepts for developing novel spintronic devices with low-power consumption and enhanced performance, and therefore bring broad technological impacts. Underrepresented undergraduate students will be recruited to participate in nanotechnology research. Exhibit and hands-on activities on nanotechnology will be developed and conducted at the annual Wisconsin Engineering Expo and at the Madison Science Museum to stimulate public's curiosity and interest in science and engineering. This project seeks to utilize isolated magnetic skyrmions in nanowires of non-centrosymmetric B20 silicides and germanides for magnetic data storage applications. Skyrmions are a novel type of exotic magnetic ordering in which electron's spins are arranged in whirlpool-like structures. Due to the topologically non-trivial spin vortex arrangement, skyrmions can be thought as free particle-like isolated magnetic domains (i.e. skyrmions outside of the skyrmion lattice) that are stable against small perturbations in magnetic field and temperature and do not pin strongly to the crystal lattice or impurities. A much lower critical current density is needed to drive the motion of skyrmions, therefore, they hold promise for next-generation magnetic storage, such as magnetic racetrack memory devices, because their nanoscale dimensions can enable high information storage density and their low threshold for current-driven motion can enable ultralow energy consumption. Skyrmions are superior over ferromagnetic domains for magnetic racetrack memory devices due to their stability and ease of manipulation with electrical current. Nanowires are ideal hosts for skyrmions since they not only serve as a natural platform for magnetic racetrack memory devices but can also potentially stabilize skyrmions. Based on the preliminary results on single-crystal nanowires of MnSi and other B20 silicides PI proposes novel device experiments to create, manipulate, and detect isolated magnetic skyrmions in nanowires by using Lorentz transmission microscopy, cantilever magnetometry, and Hall effect measurements to map the skyrmion phase diagrams in nanowires; using new magnetoresistance measurements to electrically detect confined skyrmions; nucleating isolated skyrmions using completely electrical means; and ultimately a potential demonstration of prototype skyrmion racetrack memory devices. This innovative and interdisciplinary project integrates the already developed nanowire materials with careful device studies to enable the first experimental demonstration of nucleation of skyrmions in nanowires and possible proof-of-concept magnetic racetrack memory devices based on skyrmions.