Stabilization of the skyrmion crystal phase in thin-film antiferromagnets

TL;DR

This paper demonstrates that skyrmion crystal phases can be stabilized in antiferromagnetic thin films under fieldlike torques, with potential for topological transport applications and experimental detection.

Contribution

It shows that the skyrmion lattice is the ground state in antiferromagnetic thin films under certain conditions, and explores their dynamics and topological responses.

Findings

Skyrmion crystal is the ground state in a broad phase diagram region.

Skyrmion motion can be driven by spin transfer effects.

Emergent SU(2) electromagnetic fields lead to topological spin-Hall response.

Abstract

We investigate the formation and stability of the skyrmion crystal phase in antiferromagnetic thin films subjected to fieldlike torques such as, e.g., those induced by an electric current in CuMnAs and Mn$_{2}$Au via the inverse spin-galvanic effect. We show that the skyrmion lattice represents the ground state of the antiferromagnet in a substantial area of the phase diagram, parametrized by the staggered field and the (effective) uniaxial anisotropy constant. Skyrmion motion can be driven in the crystal phase by the spin transfer effect. In the metallic scenario, itinerant electrons experience an emergent SU$(2)$-electromagnetic field associated with the (N\'{e}el) skyrmion background, leading to a topological spin-Hall response. Experimental signatures of the skyrmion crystal phase and readout schemes based on topological transport are discussed.