Magnetic skyrmions in confined nanocap geometries

Abstract

We have prepared skyrmion-hosting Ir/Fe/Co/Pt multilayer films in the form of hemispherical cap arrays and investigated the magnetic spin textures within these nanocap structures. Analysis of magnetic hysteresis loops and magnetic force microscopy images reveals that the nanocap topography plays a crucial role in shaping domain configurations, leading to the stabilization of single skyrmions per nanocap. Skyrmion arrays are nucleated with relatively small out-of-plane magnetic fields, particularly in nanocaps with smaller diameters. By tuning the nanocap diameter, the number of stabilized skyrmions can be controlled. Additionally, a reduction in the skyrmion switching fields is observed as the nanocap diameter decreases, which is attributed to an increase in effective magnetic anisotropy. Micromagnetic simulations further confirm the formation of magnetic skyrmions and demonstrate that geometric modifications can influence skyrmion stability. These findings underscore the critical role of confined geometries and multilayer structuring in tailoring the magnetic properties of skyrmion-hosting materials, providing valuable insights for future spintronic applications.