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

本计画旨在研究非中心对称金属矽化物及锗化物奈米线中的孤立磁性skyrmions，以应用于磁性资料储存。Skyrmions是一种新的磁有序结构，其中电子的自旋排列在类似于磁池的结构中。它们有望成为下一代磁信息存储，因为它们的纳米尺寸可以实现高信息存储密度和超低能耗的能力。纳米线是Skyrmion的理想宿主，因为它们不仅可以作为磁性器件的天然平台，而且还可以潜在地稳定Skyrmion。在初步结果中，PI的小组已经显示出硅化物和锗化物纳米线中skyrmions的增强的稳定性，电检测和电流驱动动力学，并提出制造新的设备来创建，操纵和检测纳米线中孤立的磁性skyrmions。这些研究的成功将证明基于Skyrmion的磁存储器件的可行性，并为开发具有低功耗和增强性能的新型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。将招募代表性不足的本科生参加纳米技术研究。 在一年一度的威斯康星州工程博览会和麦迪逊科学博物馆，将开发和进行纳米技术的展览和实践活动，以激发公众对科学和工程的好奇心和兴趣。 这个项目旨在利用非中心对称的B20硅化物和锗化物纳米线中的孤立磁性skyrmion用于磁性数据存储应用。Skyrmions是一种新型的奇异磁有序，其中电子的自旋排列在类似池塘的结构中。由于拓扑上非平凡的自旋涡旋排列，skyrmion可以被认为是自由粒子状的孤立磁畴（即skyrmion晶格外部的skyrmion），其对于磁场和温度的小扰动是稳定的，并且不会强烈地钉扎到晶格或杂质。驱动skyrmions的运动需要低得多的临界电流密度，因此，它们有望用于下一代磁存储，例如磁赛道存储器设备，因为它们的纳米尺度可以实现高信息存储密度，并且它们的电流驱动运动的低阈值可以实现超低能耗。Skyrmion上级用于磁性跑道存储器装置的铁磁畴，这归因于它们的稳定性和易于用电流操纵。纳米线是Skyrmion的理想宿主，因为它们不仅可以作为磁性赛道存储设备的天然平台，而且还可以潜在地稳定Skyrmion。基于MnSi和其他B20硅化物的单晶纳米线的初步结果，PI提出了新的器件实验，通过使用洛伦兹透射显微镜，悬臂磁力测量和霍尔效应测量来绘制纳米线中的skyrmion相图，以创建，操纵和检测纳米线中的孤立磁skyrmion;使用新的磁阻测量来电学检测受限的skyrmion;使用完全电的方式使隔离的Skyrmion成核;以及最终的原型Skyrmion赛道存储器设备的潜在演示。这个创新和跨学科的项目将已经开发的纳米线材料与仔细的器件研究相结合，以实现纳米线中skyrmions成核的首次实验演示，并可能基于skyrmions的概念验证磁性赛道存储器件。

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.