14 - Micromagnetic modeling of magnetic domain walls and domains in cylindrical nanowires

Abstract

Magnetic cylindrical nanowires are very fascinating objects where the curved geometry allows many novel magnetic effects and a variety of nontrivial magnetic structures. Micromagnetic modeling plays an important role in revealing the magnetization distribution in magnetic nanowires, often not accessible by imaging methods with sufficient details. Here, we review the magnetic properties of the shape anisotropy-dominated nanowires and the nanowires with competing shape and magnetocrystalline anisotropies, as revealed by micromagnetic modeling. We discuss the variety of magnetic walls and magnetic domains reported by micromagnetic simulations in cylindrical nanowires. The most known domain walls types are the transverse and vortex (Bloch point) domain walls and the transition between them is materials and nanowire diameter dependent. Importantly, the field or current-driven domain walls in cylindrical nanowires can achieve very high velocities. In recent simulations of nanowires with larger diameter, the skyrmion tubes are also reported. In nanowires with large saturation magnetization, the core of these tubes may form a helicoidal (“corkscrew”) structure. The topology of the skyrmion tubes play an important role in the pinning mechanism, discussed here on the example of FeCo modulated nanowires. Other discussed examples include the influence of antinotches (“bamboo” nanowires) on the remanent magnetization configurations for hcp Co and FeCo nanowires and Co/Ni multisegmented nanowires.