Magnetic vortex as a ground state for micron-scale antiferromagnetic samples

TL;DR

This paper demonstrates that micron-scale canted antiferromagnetic samples can naturally host a magnetic vortex ground state, featuring unique topological and dynamic properties, including high-frequency localized modes.

Contribution

It introduces the concept of a vortex ground state in micron-sized canted antiferromagnetic samples and analyzes their static and dynamic properties.

Findings

Ground state can be a magnetic vortex with topologically non-trivial magnetization.

Existence of high-frequency modes over hundreds of gigahertz.

Localized high-frequency mode near the vortex core.

Abstract

Here we consider micron-sized samples with any axisymmetric body shape and made with a canted antiferromagnet, like hematite or iron borate. We find that its ground state can be a magnetic vortex with a topologically non-trivial distribution of the sublattice magnetization $\vec{l}$ and planar coreless vortex-like structure for the net magnetization $\vec{M}$. For antiferromagnetic samples in the vortex state, in addition to low-frequency modes, we find high-frequency modes with frequencies over the range of hundreds of gigahertz, including a mode localized in a region of radius $\sim$ 30--40 nm near the vortex core.