Topological evolution of Multi–Vortex spin textures in amorphous magnetic architectures

Advances in understanding exotic magnetic configurations and their complex behavior are paving the way for future technologies based on magnetic nano- and microstructures. In this study, we investigate the evolution of magnetic flux closure configurations in amorphous magnetic architectures using a combination of experimental techniques and advanced micromagnetic simulations. To realize the architectures, an amorphous paramagnetic Fe89Zr11 film is first created by sputtering. Next, boron ion implantation through a mask locally transforms the paramagnetic matrix into embedded ultra-soft ferromagnetic Fe80Zr10B10 disks. With a size of a few micrometers, these disks enable the observation of large-scale flux closure structures by Kerr microscopy. By relating Kerr images and FORC diagrams, we resolve the subtle differences in the nucleation and annihilation fields of the magnetic structures yielding unique signatures for single, double, and multiple vortex configurations. A deeper understanding is provided by a large-scale micromagnetic model, which accurately reproduces the complexity of multi-vortex magnetic textures and enables a comprehensive analysis of their underlying topological properties. Hence, ion-implanted amorphous magnetic architectures can serve as a tunable platform for designing magnetic hardware that leverages topological protection to realize robust, reconfigurable, multi-state magnetic embedded elements for enhanced computational functionality.