Magnon-vortex interactions in confined ferromagnetic microstructures

Magnetic vortices are a type of domain configuration that can form in structured magnetic materials. Specifically, magnetic vortices form from magnetic energy minimization. Spins close to the center of a vortex tend to orient themselves out-of-plane to minimize energy. These regions of out-of-plane spins form a vortex core, which is a structure that has potential utility in data storage. Vortex cores can change position, chirality, and polarity by external influences, which can result in the generation of spin-waves. Magnons, the quanta of spin-waves, are propagating disturbances of electron moments and, like other waves, carry energy and momentum. In this work, we used micromagnetic simulations to investigate the dynamic effects of externally driven spin-waves on vortex cores. Simulations were conducted with MuMax³ on Permalloy structures with cell sizes of 8 nm × 8 nm × 30 nm. Spin-waves were excited by a fluctuating magnetic field in 30-nm thick strips and guided towards vortex structures in discs and squares. Our results show that spin waves can be used to drive a vortex core, which can assist in the advancement of magnonic- and vortex-based data storage devices.