Magnetic vortex as a ground state for sub-micron antiferromagnetic particles

For submicron particles shaped as any axisymmetric body and made with standard canted antiferromagnet like hematite or iron borate, the ground state may comprise of a magnetic vortex with topologically non-trivial distribution of the sublattice magnetization $\vec{l}$ and planar coreless vortex-like structure for the net magnetization $\vec{M}$. For antiferromagnetic particles in the vortex state, in addition to low-frequency modes, there are high frequency modes with frequencies over the range of hundreds gigahertz, including a mode localized in the region of the radius 30-40 nm near a vortex core.