Skyrmion Lattices Far from Equilibrium

Bauer, Andreas; Chacon, Alfonso; Halder, M.; Pfleiderer, C.

doi:10.1007/978-3-319-97334-0_5

Cited by 5 publications

(7 citation statements)

References 113 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most B20 compounds host a 2D skyrmion lattice, and are characterized by very similar H (magnetic field)– T (temperature) phase diagrams, as shown in Figure a . Magnetic interactions in these B20 compounds consist of three different components with well‐separated energy scales: the ferromagnetic exchange interaction, DM interaction arising from chiral crystal structure, and magnetic anisotropy, in order of decreasing magnitude. This energy hierarchy remains unchanged with the composition change, resulting in the common magnetic phase diagrams among B20 magnets (MnSi, FeGe, and Fe 1– x Co x Si).…”

Section: B20 Metalsmentioning

confidence: 99%

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

2017

View full text Add to dashboard Cite

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...

show abstract

Section: B20 Metalsmentioning

confidence: 99%

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

2017

View full text Add to dashboard Cite

show abstract

“…Increasing or decreasing the magnetic field ultimately results in the unwinding of the metastable skyrmions into the respective ground state. 40 Magnetic force microscopy was performed on an Omicron low-temperature ultra-high vacuum atomic force microscope equipped with RHK Technology Inc. R9controller electronics using Nanosensor SSS-QMFMR probes. In all MFM measurements, the contact potential between cantilever and sample was compensated by running a Kelvin probe force controller -see appendix A for details.…”

Section: Methodsmentioning

confidence: 99%

“…In contrast, the intrinsically slower time scales due to disorder and defects in doped systems, such as Fe 1−x Co x Si or β-Mn-type Co-Zn-Mn alloys, allow to obtain a metastable skyrmion lattice state already at moderate cooling rates. 24,[37][38][39][40] At low temperatures the dynamics of the magnetic system are completely frozen-in and the thermal energy is no longer sufficient to overcome the potential barrier that separates the skyrmion state from the topologically trivial helimagnetic states. In turn, adjusting the energy landscape by changing the applied magnetic field permits to study the topological unwinding processes and their dynamics directly in real arXiv:2103.11942v2 [cond-mat.mtrl-sci] 23 Mar 2021 space using techniques such as Lorentz transmission electron microscopy (LTEM) and magnetic force microscopy (MFM).…”

Section: Introductionmentioning

confidence: 99%

Surface pinning and triggered unwinding of skyrmions in a cubic chiral magnet

et al. 2019

Self Cite

View full text Add to dashboard Cite

In the cubic chiral magnet Fe1−xCoxSi a metastable state comprising of topologically nontrivial spin whirls, so-called skyrmions, may be preserved down to low temperatures by means of field cooling the sample. This metastable skyrmion state is energetically separated from the topologically trivial ground state by a considerable potential barrier, a phenomenon also referred to as topological protection. Using magnetic force microscopy on the surface of a bulk crystal, we show that certain positions are preferentially and reproducibly decorated with metastable skyrmions, indicating that surface pinning plays a crucial role. Increasing the magnetic field allows an increasing number of skyrmions to overcome the potential barrier, and hence to transform into the ground state. Most notably, we find that the unwinding of individual skyrmions may be triggered by the magnetic tip itself, however, only when its magnetization is aligned parallel to the external field. This implies that the stray field of the tip is key for locally overcoming the topological protection. Both the control of the position of topologically nontrivial states as well as their creation and annihilation on demand pose important challenges in the context of potential skyrmionic applications.

show abstract

“…Such an in-depth understanding, however, may not be available when investigating novel materials [14][15][16] or when phenomena such as metastable states, glassy textures, phase coexistence, topological transitions, or pronounced history dependencies play a role [17][18][19][20][21][22][23][24][25].…”

mentioning

confidence: 99%

“…1(e). Under field cooling, the skyrmion lattice may be frozen-in to lower temperatures as a metastable state [17,20,23,46]. As depicted in Fig.…”

mentioning

confidence: 99%

Ferromagnetic Resonance with Magnetic Phase Selectivity by Means of Resonant Elastic X-Ray Scattering on a Chiral Magnet

et al. 2019

View full text Add to dashboard Cite

Cubic chiral magnets, such as Cu 2 OSeO 3 , exhibit a variety of non-collinear spin textures, including a trigonal lattice of spin whirls, so-called skyrmions. Using magnetic resonant elastic x-ray scattering (REXS) on a crystalline Bragg peak and its magnetic satellites while exciting the sample with magnetic fields at GHz frequencies, we probe the ferromagnetic resonance modes of these spin textures by means of the scattered intensity. Most notably, the three eigenmodes of the skyrmion lattice are detected with large sensitivity. As this novel technique, which we label REXS-FMR, is carried out at distinct positions in reciprocal space, it allows to distinguish contributions originating from different magnetic states, providing information on the precise character, weight and mode mixing as a prerequisite of tailored excitations for applications. arXiv:1909.08293v2 [cond-mat.mtrl-sci]

show abstract

Skyrmion Lattices Far from Equilibrium

Cited by 5 publications

References 113 publications

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions

Surface pinning and triggered unwinding of skyrmions in a cubic chiral magnet

Ferromagnetic Resonance with Magnetic Phase Selectivity by Means of Resonant Elastic X-Ray Scattering on a Chiral Magnet

Contact Info

Product

Resources

About