Antiferromagnetic Skyrmion: Stability, Creation and Manipulation.

Xichao Zhang,Motohiko Ezawa,Yan Zhou

doi:10.1038/srep24795

Xichao Zhang, Motohiko Ezawa + Show 1 more

Open Access

https://doi.org/10.1038/srep24795

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Abstract

Magnetic skyrmions are particle-like topological excitations in ferromagnets, which have the topo-logical number Q = ± 1, and hence show the skyrmion Hall effect (SkHE) due to the Magnus force effect originating from the topology. Here, we propose the counterpart of the magnetic skyrmion in the antiferromagnetic (AFM) system, that is, the AFM skyrmion, which is topologically protected but without showing the SkHE. Two approaches for creating the AFM skyrmion have been described based on micromagnetic lattice simulations: (i) by injecting a vertical spin-polarized current to a nanodisk with the AFM ground state; (ii) by converting an AFM domain-wall pair in a nanowire junction. It is demonstrated that the AFM skyrmion, driven by the spin-polarized current, can move straightly over long distance, benefiting from the absence of the SkHE. Our results will open a new strategy on designing the novel spintronic devices based on AFM materials.

Highlights

Magnetic skyrmions are particle-like topological excitations in ferromagnets, which have the topological number Q = ± 1, and show the skyrmion Hall effect (SkHE) due to the Magnus force effect originating from the topology
We further show that the AFM skyrmion can move parallel to the applied current since the SkHE is completely suppressed, which is very promising for spintronic applications
We investigate the AFM system with the lattice Hamiltonian, HAFM = J ∑ mi ⋅ m j + ∑ D ⋅ − K ∑(miz )[2 ], i,j i,j i where mi represents the local magnetic moment orientation normalized as |mi| = 1, and 〈 i, j〉 runs over all the nearest neighbor sites

Summary

Introduction

Two approaches for creating the AFM skyrmion have been described based on micromagnetic lattice simulations: (i) by injecting a vertical spin-polarized current to a nanodisk with the AFM ground state; (ii) by converting an AFM domain-wall pair in a nanowire junction. It is demonstrated that the AFM skyrmion, driven by the spin-polarized current, can move straightly over long distance, benefiting from the absence of the SkHE. It does not move parallel to the injected current due to the skyrmion Hall effect (SkHE), since its topological number is ± 1. This will pose a severe challenge for realistic applications which require a straight motion of magnetic skyrmions along the direction of the applied current[13]. These results will be important from the applied perspective of magnetic skyrmions

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