Spin Textures in High-Aspect-Ratio Ni₈₀Fe₂₀ Nanodisk Arrays: Implications for Next-Generation Spintronic Devices

Recent progress in nanomagnetism has generated significant enthusiasm for the creation of high-aspect-ratio nanostructures. Nonetheless, fabricating large-area thick nanostructures encounters substantial hurdles due to inherent lithographic constraints. In this study, we showcase the fabrication of magnetic nanodisks patterned with deep UV, reaching thicknesses of up to 200 nm, accomplished through the creation of nanotrenches in the Si substrate. Subsequently, the evolution of spin texture and spin dynamics as a function of thickness (20−200 nm) has been presented. The magnetization reversal studies reveal that the disks have a vortex as their ground state configuration; the nucleation and annihilation fields associated with the vortex increase with increasing thickness. We observe an increase in the vortex core diameter as the disk thickness is increased. Micromagnetic simulations suggest that the presence of an out-of-plane magnetization component is observed along the circumference, in addition to the into-the-plane magnetization at the center for disks of higher thicknesses. The magnetization dynamics studies reveal that the center mode frequency decreases with increasing thickness, and there is a mirror symmetry in the excitation amplitude between the top and bottom layers for nanodisks with thicknesses greater than 50 nm. The results are substantiated with micromagnetic simulations. Our results open horizons in the utilization of the third dimension for emerging spin textures and their potential applications in future spintronic devices.