Strong influence of magneto-dipole interactions on size and form of antiskyrmions and skyrmions

Magnetic non-collinear spin textures that have chiral structures are of great current interest. The same type of Dzyaloshinskii-Moriya (DMI) vector exchange interactions that stabilize chiral Néel domain walls in magnetic multilayers^1-3 results in the formation of topological spin textures in bulk compounds. There has been much work on skyrmions but magnetic antiskyrmions were only recently identified, first in Mn_1.4Pt_0.9Pd_0.1Sn⁴, and, subsequently in Mn₂PtSn and Mn₂RhSn, all of which are tetragonal inverse Heusler compounds. The crystalline symmetry of these materials forces the DMI interaction to be more complex than, for example, that which stabilizes skyrmions in the cubic B20 compounds. This also ensures that anti-skyrmions are robust to temperature and magnetic field⁵. Furthermore, this also means that long range magneto-dipole interactions play a significant role in these Heuser compounds. In particular, they strongly influence the diameter of anti-skyrmions that can be varied from nanometers to microns as the thickness of lamellae of the same host material in which they are formed is varied⁶. The magnetic dipole-dipole interactions also allow for the formation of metastable “elliptical skyrmions” in this same material⁷ that have Bloch-like boundaries. Finally, we discuss our recent discovery of novel Néel like skyrmions that exist almost to room temperature in a metallic compound PtMnGa, and that are also tunable in size⁸. The size tunability of these chiral spin textures makes them especially interesting for spintronic applications.

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