Creation of skyrmions, antiskyrmions, merons and antimerons from the bubble state in a Heusler material.

It has been show experimentally [1] ,[2] that elliptical skyrmions can exist in a magnetic material which typically host antiskyrmions. Furthermore, It has been theoretically demonstrated [3] that isolated elliptical skyrmions can be nucleated in the same material with a magnetic force microscope tip from several initial states. Additional numerical simulations have demonstrated that using a combination of two magnetic force microscope tips, one can also create the non-topological bubble state. Then, when the non-topological bubble state is present, if a strong external magnetic field is applied, a pair of magnetic force microscope tips that are properly positioned and/or manipulated can create an isolated skyrmion, antiskyrmion, meron or antimeron from this bubble state, meaning there is a topological transition from zero to non-zero topological charge. This seems to happen in a system with a sufficient number of layers, such that the dipole-dipole interaction is strong enough. Initial numerical experiments show that it does not seem possible to manipulate the bubble state to create a skyrmion-antiskyrmion pair, which would otherwise preserve the topological charge.

[1] Jena J., Göbel B., Ma T., Kumar V., Saha R., Mertig I., Felser C., Parkin S.S.P., Elliptical Bloch skyrmion chiral twins in an antiskyrmion system, Nat. Comms., 11 (2020), p. 1115.

[2] Peng L., Takagi R., Koshibae W., Shibata K., Nakajima K., Arima T., Nagaosa N., Seki S., Yu X., Tokura Y., Controlled transformation of skyrmions and antiskyrmions in a non-centrosymmetric magnet, Nature Nanotechnol., 15 (2020), pp. 181-186.

[3] D. Capic, Elliptical skyrmions: Theory and nucleation by a magnetic tip in an antiskyrmion-hosting material, Journal of Magnetism and Magnetic Materials, 563, (2022),16986