Theory of vortex states in magnetic nanodisks with induced Dzyaloshinskii-Moriya interactions

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

doi:10.1103/physrevb.80.134410

Cited by 64 publications

(70 citation statements)

References 46 publications

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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%

“…where D is the Dzyaloshinskii constant, which determines the magnitude of the DMI and its sign specifies the orientation of spin spiral state owing to the DMI 18,20 . For this simulation, we adapted a three-dimensional (3D) model where the DMI exists only on the disk surfaces (top, bottom and lateral) because the DMI is considered to be localized at the surface 18,[22][23][24] .…”

Section: D Micromagnetic Modellingmentioning

confidence: 99%

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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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Section: D Micromagnetic Modellingmentioning

confidence: 99%

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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“…Unfortunately, the study of helimagnets in nanoscale is still in the infancy, and remains unexploited accordingly insofar. As a theoretical advance, the influence of the induced DM interaction on the vortex states in soft magnetic nanodisks has been investigated by Butenko et al, where the DM coupling can increase or suppress sizes of vortices depending on its chirality [18].In present paper, we theoretically investigated the magnetic microstructures in thin nanodisk of chiral magnets with DM interaction and uniaxial anisotropy by means of micromagnetic approach. A new type of vortex-like spin texture, described by a skyrmionic core with a series of circle spin stripes was obtained with free boundary conditions by minimizing the energy of the system [8,9], when the size of the nanodisk reaches a threshold value.…”

mentioning

confidence: 95%

Magnetic vortex with skyrmionic core in a thin nanodisk of chiral magnets

Du¹,

Ning²,

Tian³

et al. 2013

EPL

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-A type of vortex spin texture with skyrmionic core and a series of circle spin stripes was obtained in thin nanodisk of the chiral magnets with Dzyaloshinskii-Moriya interaction and uniaxial anisotropy by means of micromagnetic approach and Monte Carlo simulation. The size of skyrmionic core can be modulated continuously by controlling the disk size. Moreover, in some certain values of the disk size, this vortex state may be spontaneous ground state even without the help of the external magnetic field and thermal fluctuation. In addition, the uniaxial anisotropy is able to stabilize this vortex spin texture. We anticipate that the present work will inspire further experimental studies for exploring the spin structure.Nanoscale magnetic elements are always a fascinating topic in last two decades motivated by its rich physics and relevance in a variety of miniaturized spintronics device [1]. With the prospect of yielding high symmetry and reproducible spin textures for data storage or other applications, particular attention has been given to high symmetry geometries. This has been demonstrated in nanodisks of the soft magnetic material, in which the magnetic vortex states, characterized by an in-plane curling magnetization around and an out-of-plane magnetization in the core, is very stable as the ground state in a wide range of disk size [2][3][4]. The formation of the vortex states in soft-magnetic nanodisk is due to the competing interactions between the ferromagnetic exchange and magnetostatic coupling. Within this standard model the vortex states are expected to be four-fold degenerate with two possible orientations of the rotation sense of the curling inplane magnetization and polar direction of the perpendicular magnetization in the core [5,6].However, recent experimental observations using fullfield magnetic transmission soft X-ray microscopy confirmed that the vortex state in nanodisks experienced symmetry breaking mainly due to the anti-symmetry DzyaloshinskiiMoriya (DM) interaction [7], which results from the broken inversion symmetry at surfaces or interfaces of thin magnetic films, as well as low-symmetry crystals. This chiral DM interaction was shown to favour non-uniform magnetic structures [8][9][10][11]. Prominently, the nowadays so-called skyrmion, a topologically stable vortex-like spin texture with unconventional spin-electronic phenomena, has been proved to exist in helical magnets with B20 structure [12]. But, in bulk materials, skyrmions only appeared in a tiny pocket in the temperature-magnetic field (T-H) plane. In contrast, stabilized skyrmions are able to survive over a relatively wide range in the T-H plane when the dimensionality of the helimagnet is reduced from its bulk to two dimensional (2D) thin films [13,14]. The occurrence of the highly stabilized skyrmions in thin film inspired the fabrication of 2D homogeneous thickness-controllable skymionic films by evaporation methods, which provides a good basis to engineer nanoscale pattern of helimagnets for miniaturized skyrm...

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“…Other full field electron microscopies, such as X-PEEM or Lorentz-TEM would have suffered from the limitations of being able to nucleate the vortex structures from saturated states quickly. The large statistics of MTXM images allowed us to interpret the origin of the experimentally observed asymmetric phenomenon by a combination of an intrinsic Dzyaloshinskii-Moriya interaction (DMI) arising from the spin-orbit coupling [38] and surface-related "extrinsic" factors, including edge defects, surface roughness, etc. Full 3-dim micromagnetic modeling confirmed the experimental data.…”

Section: Resultsmentioning

confidence: 99%

Magnetic imaging with full-field soft X-ray microscopies

Fischer

Baldasseroni

et al. 2013

Journal of Electron Spectroscopy and Related Phenomena

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Progress toward a fundamental understanding of magnetism continues to be of great scientific interest and high technological relevance. To control magnetization on the nanoscale, external magnetic fields and spin polarized currents are commonly used. In addition, novel concepts based on spin manipulation by electric fields or photons are emerging which benefit from advances in tailoring complex magnetic materials. Although the nanoscale is at the very origin of magnetic behavior, there is a new trend toward investigating mesoscale magnetic phenomena, thus adding complexity and functionality, both of which will become crucial for future magnetic devices.Advanced analytical tools are thus needed for the characterization of magnetic properties spanning the nano-to the meso-scale. Imaging magnetic structures with high spatial and temporal resolution over a large field of view and in three dimensions is therefore a key challenge. A variety of spectromicroscopic techniques address this challenge by taking advantage of variable-polarization soft X-rays, thus enabling X-ray dichroism effects provide magnetic contrast. These techniques are also capable of quantifying in an element-, valence-and site-sensitive way the basic properties of ferro(i)-and antiferro-magnetic systems, such as spin and orbital moments, spin configurations from the nano-to the meso-scale and spin dynamics with sub-ns time resolution. This paper reviews current achievements and outlines future trends with one of these spectromicroscopies, magnetic full field transmission soft X-ray microscopy (MTXM) using a few selected examples of recent research on nano-and meso-scale magnetic phenomena. The complementarity of MTXM to X-ray photoemission electron microscopy (X-PEEM) is also emphasized.

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Theory of vortex states in magnetic nanodisks with induced Dzyaloshinskii-Moriya interactions

Cited by 64 publications

References 46 publications

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

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

Magnetic vortex with skyrmionic core in a thin nanodisk of chiral magnets

Magnetic imaging with full-field soft X-ray microscopies

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