Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

Siegfried, S.-A.; Sukhanov, A. S.; Altynbaev, E. V.; Honecker, Dirk; Heinemann, A.; Tsvyashchenko, A. V.; Grigoriev, S. V.

doi:10.1103/physrevb.95.134415

Cited by 24 publications

(17 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…2c. This vector lies in the plane of the lamella along a preferred axis determined by the present cubic anisotropy 20 . Upon application of an out-of-plane magnetic field, the SkL state is formed, illustrated in Fig.…”

mentioning

confidence: 83%

Real-space imaging of confined magnetic skyrmion tubes

et al. 2020

View full text Add to dashboard Cite

Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures 1, 2 . While they are commonly portrayed as two dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the sample 3, 4 . The study of this skyrmion tube (SkT) state is highly relevant for investigating skyrmion metastability 5 and for implementation in recently proposed magnonic computing 6 . However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the first real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure.The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigations into this unexplored dimension of the skyrmion spin texture.Skyrmion states are typically stabilised by the interplay of the ferromagnetic exchange and Zeeman energies with the Dzyalohsinskii-Moriya Interaction (DMI) 7 . In ferromagnet/heavy metal multilayer thin films, interfacial DMI is induced by symmetry-breaking spin-orbit coupling at the interface between the layers, leading to the formation of Néel-type skyrmions [8][9][10] . Bulk DMI, arising due to the lack of centrosymmetry in the underlying crystal lattice, is responsible for the formation of Bloch-type skyrmions in a range of chiral ferromagnets [11][12][13][14][15] . In crystals of these bulk materials the skyrmion state is typically only at equilibrium in a limited range of applied magnetic field and temperature just below the Curie temperature, T c , forming a hexagonal skyrmion lattice (SkL) in a plane perpendicular to the applied magnetic field.2 Figure 1 | Visualisation of the skyrmion tube spin texture. Three dimensional visualisation of three magnetic skyrmion tubes from the micromagnetic simulations presented in this paper, illustrating their extended spin structure. The inset highlights the location of the magnetic Bloch point at the end of each skyrmion tube. 3The three dimensional visualisation in Fig. 1 depicts the extended spin structure of three magnetic skyrmion tubes. The dynamics of this skyrmion tube (SkT) state play an important role in the creation and annihilation of skyrmions. For example, metastable skyrmions, which are created beyond the equilibrium thermal range by rapid field cooling 16 , are thought to unwind into topologically trivial magnetic states through the motion of a magnetic Bloch point located at the end of each individual skyrmion tube 3, 5 . Real-space observation of this dimension of the SkT state and its associated dynamics requires an in-plane magnetic field applied perpendicular to the imaging axis. Electron imaging techniques such as Fresnel Lorentz Transmission Electron Microscopy (LTEM) 12, 13 , and elec...

show abstract

mentioning

confidence: 83%

Real-space imaging of confined magnetic skyrmion tubes

et al. 2020

View full text Add to dashboard Cite

show abstract

“…FeGe also has the closest lattice match to Si [111] substrate and it can be grown by magnetron sputtering for a scalable fabrication of relevant applications. 22,24,26 While FeGe has been the object of great interest in recent imaging, transport, and neutron scattering experiments, 9,10,25,27,28 the spin dynamics of its many magnetic phases are relatively unexplored.The single crystal of B20 FeGe was grown by chemical vapor transport as described by Richardson. 29 We determined the structure and crystallographic orientation of a millimetersized, pyramid-shaped B20 FeGe crystal using Laue X-ray diffraction prior to MAS experiments (see Fig.…”

mentioning

confidence: 99%

Topological spin dynamics in cubic FeGe near room temperature

Turgut

Stolt

Jin

et al. 2017

Journal of Applied Physics

View full text Add to dashboard Cite

Understanding spin-wave dynamics in chiral magnets is a key step for the development of highspeed, spin-wave based spintronic devices that take advantage of chiral and topological spin textures for their operation. Here we present an experimental and theoretical study of spin-wave dynamics in a cubic B20 FeGe single crystal. Using the combination of waveguide microwave absorption spectroscopy (MAS), micromagnetic simulations, and analytical theory, we identify the resonance dynamics in all magnetic phases (field polarized, conical, helical, and skyrmion phases). Because the resonance frequencies of specific chiral spin textures are unique, quantitative agreement between our theoretical predictions and experimental findings for all resonance frequencies and spin wave modes enables us to unambiguously identify chiral magnetic phases and to demonstrate that MAS is a powerful tool to efficiently extract a magnetic phase diagram. These results provide a new tool to accelerate the integration of chiral magnetic materials into spintronic devices.Identifying and understanding of spin-wave excitations in chiral and topological magnetic materials is a fundamental step towards their integration into spintronic devices. Moreover, some of these materials host magnetic skyrmions, in which spins form a topologically non-trivial excitation with an integer winding number. 1,2 Magnetic skyrmions can be driven to move by spin torques with an ultralow current threshold because there is weak or no pinning, 3,4 which makes them appealing for low-power memory, 5 magnetic logic, 6 and auto-oscillator 7 devices. In support of these potential applications, magnetic skyrmions have been investigated using several methods including Lorentz transmission electron microscopy (LTEM), [8][9][10] inelastic neutron scattering, 11,12 magnetic susceptibility, 13,14 and recently by microwave absorption spectroscopy. 15,16 Microwave absorption spectroscopy (MAS), in particular, is a powerful tool for identifying and studying dynamical magnetic excitations in materials. In materials with several complex magnetic phases, such as chiral magnetic materials with a volume Dzyaloshinskii-Moriya interaction, it may be possible to use MAS to quickly establish a magnetic phase diagram because the spin texture in each magnetic phase has a unique resonance response. This specificity gives MAS an advantage as compared to electrical measurements such as the topological Hall effect, [17][18][19][20][21][22] which is more difficult to interpret because the signals are not unique to skyrmion phases or helical phases. [19][20][21][22][23][24] In this letter, we present a study of spin-wave dynamics in a single crystal of B20 FeGe using MAS. Specifically, we measure the gigahertz frequency dynamic susceptibility of FeGe using a field-referenced lock-in technique, which significantly increases our sensitivity to magnetic phase boundaries as compared to conventional MAS. 15 We observe the resonance response in all the magnetic phases (field polarized, conical, helical and...

show abstract

“…Однако величина зависящего от температуры параметра межмодового взаимодействия, определяется электронной структурой, параметрами межэлектронного взаимодействия и магнитными моментами основного состояния, которые окончательно не определены. Спиновые корреляции в окрестности T C , которые приводят к возникновению области киральных флуктуаций [6,9] и к их кроссоверу с ферромагнитными флуктуациями, исследованы недостаточно. Не рассмотрен вопрос о возможной аномалии температурной зависимости неоднородной магнитной восприимчивости при переходе в парамагнитное состояние.…”

Section: Introductionunclassified

Магнитный фазовый переход в MnSi на основе LSDA+U +SO-расчетов электронной структуры и спин-флуктуационной теории

Волков¹,

Ноговицына²,

Повзнер³

et al. 2018

Физика Твердого Тела

View full text Add to dashboard Cite

На основе спин-флуктуационной теории и LSDA + U + SO-расчетов электронной структуры исследуются спиновые состояния, возникающие в области магнитного фазового перехода в геликоидальном ферромагнетике MnSi. Получена температурная зависимость однородной магнитной восприимчивости вблизи температуры магнитного фазового перехода, которая находится в хорошем согласии с экспериментом. Определены спиновые корреляторы, соответствующие различным решениям уравнения магнитного состояния в области затянутого по температуре магнитного фазового перехода. Показано, что в этой области возникает геликоидальный ближний порядок в виде суперпозиции левых и правых спиновых спиралей со стохастическими весовыми коэффициентами. Получено, что при температуре исчезновения локальной намагниченности и переходе в парамагнитное состояние возникает расходимость магнитной восприимчивости на волновом векторе геликоида. Результаты были получены в рамках задания Mинистерства образования и науки Российской Федерации, контракт 3.9521.2017/8.9.

show abstract

Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

Cited by 24 publications

References 28 publications

Real-space imaging of confined magnetic skyrmion tubes

Real-space imaging of confined magnetic skyrmion tubes

Topological spin dynamics in cubic FeGe near room temperature

Магнитный фазовый переход в MnSi на основе LSDA+U +SO-расчетов электронной структуры и спин-флуктуационной теории

Contact Info

Product

Resources

About