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arXiv · 1904.00250

Magnetic hopfions in solids

F. N. Rybakov·N. S. Kiselev·A. B. Borisov·L. Döring·C. Melcher·S. Blügel
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Abstract

Hopfions are an intriguing class of string-like solitons, named according to a classical topological concept classifying three-dimensional direction fields. The search of hopfions in real physical systems is going on for nearly half a century, starting with the seminal work of Faddeev. But so far realizations in solids are missing. Here, we present a theory that identifies magnetic materials featuring hopfions as stable states without the assistance of confinement or external fields. Our results are based on an advanced micromagnetic energy functional derived from a spin-lattice Hamiltonian. Hopfions appear as emergent particles of the classical Heisenberg model. Magnetic hopfions represent three-dimensional particle-like objects of nanometre-size dimensions opening the gate to a new generation of spintronic devices in the framework of a truly three-dimensional architecture. Our approach goes beyond the conventional phenomenological models. We derive material-realistic parameters that serve as concrete guidance in the search of magnetic hopfions bridging computational physics with materials science.

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F. N. Rybakov, N. S. Kiselev, A. B. Borisov, L. Döring, C. Melcher, S. Blügel. 2019-03-30. Magnetic hopfions in solids. https://doi.org/10.1063/5.0099942

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