Frustrated magnetic vortices in a triad of permalloy rings: Magneto-optical Kerr effect, magnetic force microscopy, and micromagnetic simulations

摘要

The field dependent magnetization of three mutually touching permalloy rings were investigated by means of the magneto-optical Kerr effect, magnetic force microscopy, and micromagnetic simulations. Each ring has a width of 0.2-1.8 mu m, an outer diameter of 4 mu m, and a thickness of 17 nm. Decreasing an applied magnetic field from saturation leads to the nucleation and annihilation of magnetic vortices, leaving at least one ring in a magnetically frustrated state. The properties of the magnetization reversal strongly depend on the ring width and on the direction of the applied field. Multiple complex reversal paths with vortexlike magnetization configurations are found.