Single Chiral Skyrmions in Ultrathin Magnetic Films.

Konstantin Guslienko,Arantxa Aranda

doi:10.3390/ma11112238

Abstract

The stability and sizes of chiral skyrmions in ultrathin magnetic films are calculated accounting for the isotropic exchange, Dzyaloshinskii–Moriya exchange interaction (DMI), and out-of-plane magnetic anisotropy within micromagnetic approach. Bloch skyrmions in ultrathin magnetic films with B20 cubic crystal structure (MnSi, FeGe) and Neel skyrmions in ultrathin films and multilayers Co/X (X = Ir, Pd, Pt) are considered. The generalized DeBonte ansatz is used to describe the inhomogeneous skyrmion magnetization. The single skyrmion metastability/instability area, skyrmion radius, and skyrmion width are found analytically as a function of DMI strength . It is shown that the single chiral skyrmions are metastable in infinite magnetic films below a critical value of DMI , and do not exist at . The calculated skyrmion radius increases as increases and diverges at , whereas the skyrmion width increases monotonically as increases up to without any singularities. The calculated skyrmion width is essentially smaller than the one calculated within the generalized domain wall model.

Highlights

The individual magnetic skyrmions have attracted considerable attention from researchers assuming potential applications in spintronic and information processing devices [1]
The chiral magnetic skyrmions are a kind of magnetic topological soliton [2] in 2D spin systems characterized by a non-zero skyrmion number defined as
Following the ideas of Dzyaloshinskii [4], in Ref. [5] it was found that adding the term D [m · (∇ × m)] to the magnetic energy density of an infinite cubic ferromagnet leads to the stabilization of an inhomogeneous magnetization texture for any finite value of the Dzyaloshinskii–Moriya exchange interaction (DMI)

Summary

Introduction

The individual (single) magnetic skyrmions have attracted considerable attention from researchers assuming potential applications in spintronic and information processing devices [1]. [5] it was found that adding the term D [m · (∇ × m)] (linear in spatial derivatives of magnetization) to the magnetic energy density of an infinite cubic ferromagnet leads to the stabilization of an inhomogeneous magnetization texture for any finite value of the DMI parameter D. Such terms are allowed in magnetic crystals whose symmetry group lacks the space inversion symmetry operation It was Materials 2018, 11, 2238; doi:10.3390/ma11112238 www.mdpi.com/journal/materials

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Results

Conclusion