Influence of the Dzyaloshinskii-Moriya interaction on vortex states in magnetic nanodisks

Butenko, A. B.; Leonov, A. A.; Bogdanov, A. N.; Rößler, U.

doi:10.1088/1742-6596/200/4/042012

Cited by 9 publications

(9 citation statements)

References 8 publications

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“…These solutions well represent the vortexcore properties for any R d l e . As shown previously, homogeneous surface-induced DM couplings favour vortices with the same chirality [15], [16] slope θ ρ becomes negative, and the magnetization structure changes its local chirality. After that the polar angle θ(ρ) monotonically approaches the limiting value θ h .…”

Section: Vortex Solutions and Magnetization Profilessupporting

confidence: 75%

“…In this area induced local magnetic anisotropy likely predominates other interactions and we assume a homogeneously magnetized solution θ(ρ < δ) ≡ 0. In the limit of ρ → R d with R d l e the energy of the vortex in a nanodisk with a dislocation w (d) (10) converges towards the value of energy for vortices in a defect-free nanodisk [15], [16]. Correspondingly, for the finite disk, free boundary conditions g(θ, R d ) = 0 can be used.…”

Section: Joint European Magnetic Symposia 2012mentioning

confidence: 99%

“…The procedure for deriving the solutions of boundary problem (11) and (12) is the same as for dislocation-free nanodisks described in Refs. [15], [16]. …”

Section: Joint European Magnetic Symposia 2012mentioning

confidence: 99%

“…It has been proposed to use both the up and down polarities, i.e., the perpendicular magnetization of the vortex, or the rotation sense of the curling in-plane magnetization as switchable bit elements in memory devices [13], [14]. In previous work [15,16], we have shown that the homogeneous surfaceinduced DM interactions lift the degeneracy between the four possible vortex states and leads to a chirality selection between the states connected by a global parity change, owing to the broken inversion symmetry at surfaces. This effect will be strongest in ultrathin and clean single-crystalline film elements.…”

Section: Introductionmentioning

confidence: 99%

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Chirality selection in the vortex state of magnetic nanodisks with a screw dislocation

Butenko

Rößler

2013

EPJ Web of Conferences

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Abstract. Structural defects in magnetic crystalline materials may locally change magnetic properties and can significantly influence the behavior of magnetic nanostructures. E.g., surface-induced Dzyaloshinskii-Moriya interactions can strongly affect vortex structures in magnetic nanodisks causing a chirality selection. Near lattice defects, the spin-orbit interactions induce local antisymmetric Dzyaloshinskii-Moriya exchange and cause effective anisotropies, which can result in spin canting. Broken inversion symmetry near a defect leads to locally chiral exchange. We present a phenomenological approach for dislocation-induced Dzyaloshinskii-Moriya couplings.As an example we investigate effects of a screw dislocation at the center of a magnetic nanodisk with a vortex state. By numerical calculations on vortex profiles we analyze equilibrium parameters of the vortex as functions of applied magnetic field and the material and geometrical parameters. It is proposed that magnetic nanodisks with defects provide a suitable experimental setting to study induced chirality by spin-orbit effects.

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Section: Vortex Solutions and Magnetization Profilessupporting

confidence: 75%

Section: Joint European Magnetic Symposia 2012mentioning

confidence: 99%

“…The procedure for deriving the solutions of boundary problem (11) and (12) is the same as for dislocation-free nanodisks described in Refs. [15], [16]. …”

Section: Joint European Magnetic Symposia 2012mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chirality selection in the vortex state of magnetic nanodisks with a screw dislocation

Butenko

Rößler

2013

EPJ Web of Conferences

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“…The DMI has been discussed as the origin for spin spiral textures and has been theoretically predicted to affect the shape and size of magnetic vortices 20,21 . To explore the effect of DMI on the asymmetric formation process of VS, we calculated the generation probabilities of each VS by performing a micromagnetic simulation of the magnetization process of a nanodisk from saturated state to zero-field state.…”

Section: D Micromagnetic Modellingmentioning

confidence: 99%

Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk

et al. 2012

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The magnetic vortex in nanopatterned elements is currently attracting enormous interest. A priori, one would assume that the formation of magnetic vortex states should exhibit a perfect symmetry, because the magnetic vortex has four degenerate states. Here we show the first direct observation of an asymmetric phenomenon in the formation process of vortex states in a permalloy nanodisk using high-resolution full-field magnetic transmission soft X-ray microscopy. micromagnetic simulations confirm that the intrinsic Dzyaloshinskii-moriya interaction, which arises from the spin-orbit coupling due to the lack of inversion symmetry near the disk surface, as well as surface-related extrinsic factors, is decisive for the asymmetric formation of vortex states.

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Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

2017

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with n = m/|m| being an unit vector parallel to the local magnetic moment m. [10,11] This means that the arrangement of spins within a single skyrmion can wrap a sphere nonzero integer times. The case of Φ = ± 1 is exemplified in Figure 1a, which suggests the topologically protected nature of the skyrmion spin texture.To stabilize such magnetic skyrmions, several different approaches have been proposed. For example, the interplay between the magnetic dipole-dipole interaction and uniaxial magnetic anisotropy often leads to the formation of a cylindrical magnetic domain structure termed magnetic bubble, [15][16][17][18] which is known to host various integer skyrmion numbers in cases depending on the detail of the internal spin texture. [19][20][21] The magnetic bubble was once utilized as the information carrier for magnetic storage devices (i.e., magnetic bubble memory), which was commercially available in the 1980s but later discontinued partly because the relatively large size of the magnetic bubble (≈1 μm) prevents further improvement of information density. Some latest studies suggest the possible miniaturization of bubble size down to sub-micron scale in multi-layered thin films with finely tuned magnetic parameters. [22,23] More recently, the experimental discovery of nanometric skyrmions has been reported for a series of ferromagnets with noncentrosymmetric crystal structure, where antisymmetric exchange interaction, i.e. Dzyaloshinskii-Moriya (DM) interaction, [24,25] originating from relativistic spin-orbit interaction plays a key role for the skyrmion formation. In this case, the size of skyrmion or the associated magnetic modulation period λ is determined by the ratio between the magnitudes of DM interaction D and ferromagnetic exchange interaction J in form of λ ∝ J/D, which typically ranges from 1 to 100 nm. The internal spin texture of magnetic skyrmions essentially depends on the symmetry of the underlying crystallographic lattice and associated DM interaction. [8,26] So far, most of the single-component materials showing magnetic skyrmions possess a chiral crystal structure, where Bloch-type skyrmions with a vortex-like swirling spin texture (Figure 1b) are observed. [10,12,[27][28][29][30] In contrast, under the uniaxial polar crystal structure, [31] the emergence of Néel type skyrmion with radial spin texture (Figure 1c) has been proposed. [8,26,32] Bloch (Néel) type skyrmions can form close-packed 2D hexagonal lattice (Figure 1f), which can be viewed as the superposition The concept of a skyrmion, which was first introduced by Tony Skyrme in the field of particle physics, has become widespread in condensed matter physics to describe various topological orders. Skyrmions in magnetic materials have recently received particular attention; they represent vortex-like spin structures with the character of nanometric particles and produce fascinating physical properties rooted in their topological nature. Here, a series of noncentrosymmetric ferromagnets hosting skyrmions is reviewed: B20 metals, Cu...

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Influence of the Dzyaloshinskii-Moriya interaction on vortex states in magnetic nanodisks

Cited by 9 publications

References 8 publications

Chirality selection in the vortex state of magnetic nanodisks with a screw dislocation

Chirality selection in the vortex state of magnetic nanodisks with a screw dislocation

Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

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