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.
