Magnetic textures with particle properties beyond skyrmions: chiral bobbers, globules, and hopfions
Invited
Abstract
Magnetic crystals with competing interactions allow the existence of localized magnetic textures possessing a lot of similarities to ordinary particles meaning that they can move and interact with each other: attract, repel, or mutually annihilate. In my presentation, I discuss a wide variety of different types of such textures existing in magnetic crystals.
First, I will discuss the chiral magnets where the competition between the Heisenberg exchange and the Dzyaloshinsky-Moriya interactions leads to the emergence of magnetic skyrmions (Sks). Recently we have shown that besides ordinary Sk [1], the micromagnetic functional for chiral magnets admits an infinite number of solutions with different topological charges, energies, static, and dynamical properties [2].
We have shown theoretically [3] and experimentally [4] that in 3D crystals of isotropic chiral magnets besides Sk tubes (SkTs) penetrating through the whole sample, there are also other types of solutions, so-called hybrid solitons (HSs) [3]. HSs are topologically trivial objects, which can be thought of as a SkT with one end – chiral bobber [3,4] or two ends – magnetic globule [5], where the ends are magnetic singularities – Bloch points.
In the final part, I will discuss true 3D to topological magnetic solitons or magnetic hopfions [6,7]. The magnetic hopfions can be thought of as SkTs with closed ends. Such closed tubes, in general, have the shape of complex mathematical knots. I present the micromagnetic functional [8] and magnetic interactions allowing the stability of these objects and discuss the static and dynamic properties of these objects.
[1] A. N. Bogdanov & D. A. Yablonskii Sov. Phys. JETP 68, 101 (1989).
[2] F. N. Rybakov & N. S. Kiselev Phys. Rev. B 99, 064437 (2019).
[3] F. N. Rybakov, et al., Phys. Rev. Lett. 115, 117201 (2015).
[4] F. Zheng, et al., Nat. Nanotechnol. 13 451 (2018).
[5] G. P. Müller, et al., arXiv:1903.12446.
[6] http://hopfion.com/
[7] F. N. Rybakov, et al., arXiv:1904.00250.
First, I will discuss the chiral magnets where the competition between the Heisenberg exchange and the Dzyaloshinsky-Moriya interactions leads to the emergence of magnetic skyrmions (Sks). Recently we have shown that besides ordinary Sk [1], the micromagnetic functional for chiral magnets admits an infinite number of solutions with different topological charges, energies, static, and dynamical properties [2].
We have shown theoretically [3] and experimentally [4] that in 3D crystals of isotropic chiral magnets besides Sk tubes (SkTs) penetrating through the whole sample, there are also other types of solutions, so-called hybrid solitons (HSs) [3]. HSs are topologically trivial objects, which can be thought of as a SkT with one end – chiral bobber [3,4] or two ends – magnetic globule [5], where the ends are magnetic singularities – Bloch points.
In the final part, I will discuss true 3D to topological magnetic solitons or magnetic hopfions [6,7]. The magnetic hopfions can be thought of as SkTs with closed ends. Such closed tubes, in general, have the shape of complex mathematical knots. I present the micromagnetic functional [8] and magnetic interactions allowing the stability of these objects and discuss the static and dynamic properties of these objects.
[1] A. N. Bogdanov & D. A. Yablonskii Sov. Phys. JETP 68, 101 (1989).
[2] F. N. Rybakov & N. S. Kiselev Phys. Rev. B 99, 064437 (2019).
[3] F. N. Rybakov, et al., Phys. Rev. Lett. 115, 117201 (2015).
[4] F. Zheng, et al., Nat. Nanotechnol. 13 451 (2018).
[5] G. P. Müller, et al., arXiv:1903.12446.
[6] http://hopfion.com/
[7] F. N. Rybakov, et al., arXiv:1904.00250.
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Presenters
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Nikolai S. Kiselev
Institute for Advanced Simulation, Forschungszentrum Julich GmbH, Forschungszentrum Jülich, Germany
Authors
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Nikolai S. Kiselev
Institute for Advanced Simulation, Forschungszentrum Julich GmbH, Forschungszentrum Jülich, Germany