Skyrmion-based magnetic devices for advanced spintronic applications

Abstract

Spintronic technology has garnered a great deal of interest, particularly about the topological spin structures referred to magnetic skyrmion. Among the spintronic applications, skyrmions are thought utilizing for future information applications by reasons that skyrmions have predicted stability and very small nanoscale size, as well as their extremely low driving current density. The proposal for producing, transporting, and manipulating skyrmions have been reported, and they imply various prospective benefits for skyrmion devices in comparison to other related applications, like racetrack memory and spin torque nano-oscillator. However, there are some challenges on the skyrmion about the skyrmion wide applications. The Magnus force and skyrmion Hall effect will result in devastation about skyrmion-based devices, resulting the detrimental influence on the performance of skyrmion-based spintronics applications. This thesis addresses the proceeding constraints through the structural and operational optimizations. Firstly, the skyrmion's properties needs to be thoroughly explored for better comprehension. The manipulation of skyrmion motion by changing spin torque parameters with in-plane magnetic field requires more research, however the skyrmion is extremely promising for real-world applications. On the skyrmion motion, the influences of an appropriately external field, spin torque coefficients, and spin polarization orientations were investigated. Micromagnetic simulations have demonstrated the skyrmion static and dynamic characteristics with magnetic field. The spin torque nano-oscillator of skyrmion-based has been proposed for usage in next-generation spintronic devices due to its high and stable maximum operating frequency and increased tenability. The Magnus force would be induced to exert a skyrmion drive to the center or edge of a nanodisk, resulting in the skyrmion annihilation at the nanodisk’s edge and a decrease of oscillator performance. To solve this issue, I design a spin torque nano-oscillator model with concentric circles structure. The nanodisk will be divided into two areas, which have different perpendicular magnetic anisotropy or Dzyaloshinskii-Moriya interaction coefficients. The skyrmions would have stable motion along the boundary between two regions. It is possible to determine the maximum frequency of skyrmion oscillation. Racetrack memory is a potential candidate for high-density information storage with no mechanical components and hence more appropriate for solid-state circuits, is also one of the most extensively reported skyrmion-based applications. In contrast, the skyrmion Hall effect would be detrimental in future skyrmion applications, since it causes skyrmions to deviate from the motion direction and causes their annihilation at the sample edge. Skyrmion-based racetrack memory devices have been designed as a model without skyrmion Hall effect is a crucial subject. Study statistically a voltage gate channel on a bilayer nanostructure in which the skyrmion hall effect is avoided by altering perpendicular magnetic anisotropy coefficients and spin polarization angles. Through the results and discussions on the features of the skyrmion and its extensive applications as a nano-oscillator and racetrack memory. These structures' performances have been considerably improved. The applications of skyrmion-based spintronics devices would benefit from my findings.