Vortex-state in Iron Nanodisks: Formation and Response in Water Solutions

The magnetic vortex state has been widely studied in soft magnetic alloys such as Permalloy (Ni
80
Fe
20
). However, the morphological conditions for this unique spin configuration in single-element Fe nanodisks are not defined yet. Fe is an interesting material for magnetic-based biomedical applications due to its biocompatibility and high magnetization. This work investigates the spin structure of Fe nanodisks as a function of thickness and diameter. Nanodisks were fabricated with thicknesses of 20 - 150 nm and diameters of 300 - 1000 nm. Magnetometry measurements allowed us to determine the geometrical conditions for the formation of a spin-vortex configuration. Furthermore, the magnetic response of Fe-nanodisks in water solutions was analyzed at low frequency magnetic fields. The results bound the dynamic limits of these nanostructures in biomedical applications.