Tunable skyrmion-skyrmion binding on the surface of a topological insulator

Abstract

We show that skyrmions on the surface of a magnetic topological insulator may experience an attractive interaction that leads to the formation of a skyrmion-skyrmion bound state. This is in contrast to the case of skyrmions in a conventional chiral ferromagnet, for which the intrinsic interaction is repulsive. The origin of skyrmion binding in our model is the molecular hybridization of topologically protected electronic orbitals associated with each skyrmion. Attraction between the skyrmions can therefore be controlled by tuning a chemical potential that populates/depopulates the lowest-energy molecular orbital. We find that the skyrmion-skyrmion bound state can be made stable, unstable, or metastable depending on the chemical potential, magnetic field, and easy-axis anisotropy of the underlying ferromagnet, resulting in a rich phase diagram. Finally, we discuss the possibility to realize this effect in a recently synthesized Cr doped ${\left({\mathrm{Bi}}_{2-y}{\mathrm{Sb}}_y\right)}_2{\mathrm{Te}}_3$ heterostructure.

arXiv comment12 pages, 8 figures; v2: Updated to address referee comments, minor stylistic changes. Published version

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• Resonant optical topological Hall conductivity from skyrmions
• Finite temperature fluctuation-induced order and responses in magnetic topological insulators
• Charged magnons on the surface of a topological insulator
• Interface-Induced Stability of Nontrivial Topological Spin Textures: Unveiling Room-Temperature Hopfions and Skyrmions
• Chiral electronic network within skyrmionic lattice on topological insulator surfaces
• Spatial decay of isolated magnetic hopfions in chiral helimagnets