Theory of vortex states in magnetic nanodisks with induced Dzyaloshinskii-Moriya interactions

Broken inversion symmetry in magnetic nanostructures induces Dzyaloshinskii-Moriya couplings. In the presence of surfaces/interfaces the magnetism of magnetic nanodisks can be essentially affected by these chiral couplings. Within a micromagnetic approach we calculate the equilibrium sizes and shape of the vortices as functions of magnetic field, the material, and the geometrical parameters of nanodisks. It was found that the Dzyaloshinskii-Moriya coupling can considerably increase sizes of vortices with right chirality and suppress vortices with opposite chirality. This allows to form a bistable system of vortices with the same chirality as a basic element for storage applications.