Symmetry breaking in the formation of magneticvortex states in a permalloy nanodisk

摘要

The magnetic vortex in nanopatterned elements is currently attracting enormous interest.A priori, one would assume that the formation of magnetic vortex states should exhibit aperfect symmetry, because the magnetic vortex has four degenerate states. Here we showthe first direct observation of an asymmetric phenomenon in the formation process of vortexstates in a permalloy nanodisk using high-resolution full-field magnetic transmission softX-ray microscopy. micromagnetic simulations confirm that the intrinsic Dzyaloshinskii–moriyainteraction, which arises from the spin-orbit coupling due to the lack of inversion symmetrynear the disk surface, as well as surface-related extrinsic factors, is decisive for the asymmetricformation of vortex states.