The Properties of Isolated Magnetic Vortices

Bocdanov, A.; Hubert, A.

doi:10.1002/pssb.2221860223

Cited by 188 publications

(261 citation statements)

References 30 publications

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“…The spin configuration forming a hedgehog is also due to the DMI. Second, a skyrmion is stabilized dynamically by the DMI 16,17 . Although the topological number Q is defined even without the DMI, it does not have any role if a hedgehog spin configuration is not formed to generate Q ¼ 1.…”

Section: Resultsmentioning

confidence: 99%

“…Recent experimental observation of skyrmions in chiral ferromagnet evokes a flourish of its extensive study [3][4][5][6][7][8][9][10][11][12][13][14][15] . It is stabilized dynamically by the Dzyaloshinskii-Moriya interaction (DMI) and external magnetic field [16][17][18][19][20] . Once it is created, its stability is topologically protected against dissipation and fluctuation even in the presence of large defects 2,21 .…”

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confidence: 99%

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A reversible conversion between a skyrmion and a domain-wall pair in a junction geometry

2014

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Skyrmions are expected to be a key component of the next-generation of spintronics: known as 'skyrmionics'. On the other hand, there is a well-established memory device encoded by a sequence of domain walls. Here we show a conversion is possible between a skyrmion and a domain-wall pair by connecting wide and narrow nanowires, enabling the information transmission between a skyrmion device and a domain-wall device. Our results will be the basis of a hybrid device made of skyrmions and domain walls, where the encoded information in domain walls is converted into skyrmions, and then read out by converting the skyrmions back to domain walls after a functional control of the skyrmions. Such a device has the potential to outperform domain-wall racetrack memory because of the combined advantages of domain walls and skyrmions for spintronics application.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

A reversible conversion between a skyrmion and a domain-wall pair in a junction geometry

2014

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“…Secondly, GVS exhibits an interesting magnetic cycloidal order between T FM and T N = 13 K, which can be transformed by a moderate magnetic field (of about 40 mT) into a Néel-type skyrmion lattice (SkL) phase [2]. As predicted in the seminal works of Bogdanov et al [3][4][5] the important prerequisite for the appearance of this very unusual spin texture (Néel-type SkL) is the polar macroscopic symmetry of the underlying crystal lattice. In GVS, the suitable C 3v symmetry emerges together with the ferroelectric polarization below the JahnTeller phase transition T JT = 42 K [6,7].…”

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confidence: 97%

Lattice modes and the Jahn-Teller ferroelectric transition ofGaV4S8

et al. 2016

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Crystal of GaV 4 S 8 , a multiferroic system hosting a Néel-type skyrmion lattice phase, has been investigated by polarized Raman and IR spectroscopy above and below the ferroelectric phase transition. Counts of the observed IR and Raman-active modes belonging to distinct irreducible representations agree quite well with group-theory predictions. Phonon spectra are assigned and interpreted with the aid of ab initio calculations of the phonon spectra in the ferroelectric phase. Results allow appreciation of phonon frequencies of the modes involved in Jahn-Teller distortion and their contribution to the spontaneous polarization. DOI: 10.1103/PhysRevB.94.060104 The ternary chalcogenide GaV 4 S 8 (GVS) has recently attracted considerable attention due to its multiferroic properties. First of all, the low-temperature zero-field phase of GVS is simultaneously ferroelectric and ferromagnetic up to about T FM ≈ 5 K. Its magnetization corresponds to S = 1/2 per formula unit and its electric polarization is also appreciable (P s ≈ 1 μC cm −2 ). Moreover, clear experimental evidence has been found for a sizable magnetoelectric coupling [1]. Secondly, GVS exhibits an interesting magnetic cycloidal order between T FM and T N = 13 K, which can be transformed by a moderate magnetic field (of about 40 mT) into a Néel-type skyrmion lattice (SkL) phase [2]. As predicted in the seminal works of Bogdanov et al. [3][4][5] the important prerequisite for the appearance of this very unusual spin texture (Néel-type SkL) is the polar macroscopic symmetry of the underlying crystal lattice. In GVS, the suitable C 3v symmetry emerges together with the ferroelectric polarization below the JahnTeller phase transition T JT = 42 K [6,7]. This unusual phase transition was shown to be driven by a strong electron-phonon coupling between the unpaired electron in the highest-energy, orbitally degenerate electronic state of the V 4 cluster and two corresponding Jahn-Teller-active zone-center modes of the noncentrosymmetric paraelectric structure of GVS [8].The aim of this Rapid Communication is to explore the role of the zone-center phonon modes in the phase transition using Raman and IR spectroscopy and the ab initio approach. In particular, we have (i) determined the spectrum of zonecenter phonon modes of GVS, (ii) identified two phonon modes primarily involved in the phase transition, and (iii) related these findings to the Jahn-Teller phase transition and dielectric properties of GVS.GVS is a lacunar spinel, i.e., it can be presented as a spinel structure lacking every second Ga atom. It can be viewed as a face-centered cubic (fcc) lattice formed of * hlinka@fzu.cz tetrahedral GaS 4 and cubane V 4 S 4 clusters [see Fig. 1(a)]. The paraelectric phase of GaV 4 S 8 has a noncentrosymmetric cubic (T d ) symmetry [6]. The hybridization of the valence states of the vanadium metal ions within the V 4 S 4 magnetic building blocks leads to one unpaired localized electron occupying a triply degenerate t 2 cluster orbital with an overall spin 1/2. The Ga...

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“…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].…”

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confidence: 98%

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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The Properties of Isolated Magnetic Vortices

Cited by 188 publications

References 30 publications

A reversible conversion between a skyrmion and a domain-wall pair in a junction geometry

A reversible conversion between a skyrmion and a domain-wall pair in a junction geometry

Lattice modes and the Jahn-Teller ferroelectric transition ofGaV4S8

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

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