Periodically modulated skyrmion strings in Cu2OSeO3

AbstractMagnetic skyrmions are vortex-like spin textures, which are usually treated as two-dimensional objects. In their lattice state, they form well-ordered, hexagonal structures, which have been studied in great detail. To obtain a three-dimensional (3D) skyrmion crystal, these planes can be envisaged to be stacked up forming skyrmion strings in the third dimension. Here, we report the observation of a 3D skyrmion phase in Cu2OSeO3 by carrying out reciprocal space mapping in resonant elastic x-ray scattering. We observe regions in the magnetic field-cooling phase diagram in which the skyrmion phase apparently coexists with the conical phase. However, such a coexistence is forbidden due to symmetry arguments. Instead, the skyrmion strings themselves are periodically modulated along their axes, as confirmed by micromagnetic simulations. The periodic modulation is in fact a necessary consequence of the evolution of the skyrmion phase out of the conical state and should therefore be a universal property of skyrmion strings in chiral helimagnets.

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Instrumentation For Quantitative Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078584 ◽

1977 ◽

Vol 35 ◽

pp. 206-209

Author(s):

B. Ralph ◽

A.R. Jones

Keyword(s):

Volume Fraction ◽

Three Dimensional ◽

Two Dimensional ◽

Automatic Data ◽

Phase Volume Fraction ◽

Statistical Confidence ◽

Resultant Data ◽

Automatic Data Collection ◽

Third Dimension ◽

Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

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Deriving the skyrmion Hall angle from skyrmion lattice dynamics

Nature Communications ◽

10.1038/s41467-021-22857-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

R. Brearton ◽

L. A. Turnbull ◽

J. A. T. Verezhak ◽

G. Balakrishnan ◽

P. D. Hatton ◽

...

Keyword(s):

High Efficiency ◽

Magnetic Field Gradient ◽

Real Space ◽

Magnetic Multilayer ◽

Multilayer Systems ◽

Space Technique ◽

Hall Angle ◽

Lattice State ◽

The Many ◽

Magnetic Skyrmions

AbstractMagnetic skyrmions are topologically non-trivial, swirling magnetization textures that form lattices in helimagnetic materials. These magnetic nanoparticles show promise as high efficiency next-generation information carriers, with dynamics that are governed by their topology. Among the many unusual properties of skyrmions is the tendency of their direction of motion to deviate from that of a driving force; the angle by which they diverge is a materials constant, known as the skyrmion Hall angle. In magnetic multilayer systems, where skyrmions often appear individually, not arranging themselves in a lattice, this deflection angle can be easily measured by tracing the real space motion of individual skyrmions. Here we describe a reciprocal space technique which can be used to determine the skyrmion Hall angle in the skyrmion lattice state, leveraging the properties of the skyrmion lattice under a shear drive. We demonstrate this procedure to yield a quantitative measurement of the skyrmion Hall angle in the room-temperature skyrmion system FeGe, shearing the skyrmion lattice with the magnetic field gradient generated by a single turn Oersted wire.

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X-ray imaging with ultra-small-angle X-ray scattering as a contrast mechanism

Journal of Applied Crystallography ◽

10.1107/s0021889804016073 ◽

2004 ◽

Vol 37 (5) ◽

pp. 757-765 ◽

Cited By ~ 28

Author(s):

L. E. Levine ◽

G. G. Long

Keyword(s):

Small Angle ◽

Imaging Technique ◽

Three Dimensional ◽

Sample Volume ◽

Contrast Imaging ◽

X Ray ◽

X Ray Scattering ◽

X Ray Imaging ◽

Contrast Mechanism ◽

Ray Scattering

A new transmission X-ray imaging technique using ultra-small-angle X-ray scattering (USAXS) as a contrast mechanism is described. USAXS imaging can sometimes provide contrast in cases where radiography and phase-contrast imaging are unsuccessful. Images produced at different scattering vectors highlight different microstructural features within the same sample volume. When used in conjunction with USAXS scans, USAXS imaging provides substantial quantitative and qualitative three-dimensional information on the sizes, shapes and spatial arrangements of the scattering objects. The imaging technique is demonstrated on metal and biological samples.

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Theory of Electron Diffraction by Crystals

Zeitschrift für Naturforschung A ◽

10.1515/zna-1967-0402 ◽

1967 ◽

Vol 22 (4) ◽

pp. 422-431 ◽

Cited By ~ 111

Author(s):

Kyozaburo Kambe

Keyword(s):

Integral Equation ◽

Electron Diffraction ◽

General Theory ◽

Green’S Function ◽

Green's Function ◽

Scattering Problem ◽

Three Dimensional ◽

Two Dimensions ◽

The Third ◽

Third Dimension

A general theory of electron diffraction by crystals is developed. The crystals are assumed to be infinitely extended in two dimensions and finite in the third dimension. For the scattering problem by this structure two-dimensionally expanded forms of GREEN’S function and integral equation are at first derived, and combined in single three-dimensional forms. EWALD’S method is applied to sum up the series for GREEN’S function.

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Analysis of an origin of DNA amplification in Sciara coprophila by a novel three-dimensional gel method

Molecular and Cellular Biology ◽

10.1128/mcb.14.2.1520-1529.1994 ◽

1994 ◽

Vol 14 (2) ◽

pp. 1520-1529

Author(s):

C Liang ◽

S A Gerbi

Keyword(s):

Three Dimensional ◽

Dna Amplification ◽

Gel Method ◽

Dna Molecule ◽

Cutting Out ◽

Origin Region ◽

2D Gel ◽

Third Dimension ◽

Single Dna Molecule ◽

Replication Intermediates

The replication origin region for DNA amplification in Sciara coprophila DNA puff II/9A was analyzed with a novel three-dimensional (3D) gel method. Our 3D gel method involves running a neutral/neutral 2D gel and then cutting out vertical gel slices from the area containing replication intermediates, rotating these slices 90 degrees to form the third dimension, and running an alkaline gel for each of the slices. Therefore, replication intermediates are separated into forks and bubbles and then are resolved into parental and nascent strands. We used this technique to determine the size of forks and bubbles and to confirm the location of the major initiation region previously mapped by 2D gels to a 1-kb region. Furthermore, our 3D gel analyses suggest that only one initiation event in the origin region occurs on a single DNA molecule and that the fork arc in the composite fork-plus-bubble pattern in neutral/neutral 2D gels does not result from broken bubbles.

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Magnetic Field Structure of Star Forming Regions: VLBI Spectral Line Results

Symposium - International Astronomical Union ◽

10.1017/s0074180900078426 ◽

1984 ◽

Vol 110 ◽

pp. 333-334

Author(s):

J.A. Garcia-Barreto ◽

B. F. Burke ◽

M. J. Reid ◽

J. M. Moran ◽

A. D. Haschick

Keyword(s):

Magnetic Field ◽

Three Dimensional ◽

Aperture Synthesis ◽

Stokes Parameters ◽

Hii Region ◽

Star Forming ◽

Star Forming Regions ◽

Vlbi Observations ◽

The Magnetic Field ◽

Synthesis Experiment

Magnetic fields play a major role in the general dynamics of astronomical phenomena and particularly in the process of star formation. The magnetic field strength in galactic molecular clouds is of the order of few tens of μG. On a smaller scale, OH masers exhibit fields of the order of mG and these can probably be taken as representative of the magnetic field in the dense regions surrounding protostars. The OH molecule has been shown to emit highly circular and linearly polarized radiation. That it was indeed the action of the magnetic field that would give rise to the highly polarized spectrum of OH has been shown by the VLBI observations of Zeeman pairs of the 1720 and 6035 MHz by Lo et. al. and Moran et. al. VLBI observations of W3 (OH) revealed that the OH emission was coming from numerous discrete locations and that all spots fell within the continuum contours of the compact HII region. The most detailed VLBI aperture synthesis experiment of the 1665 MHz emission from W3 (OH) was carried out by Reid et. al. who found several Zeeman pairs and a characteristic maser clump size of 30 mas. In this work, we report the results of a 5 station VLBI aperture synthesis experiment of the 1665 MHz OH emission from W3 (OH) with full polarization information. We produced VLBI synthesis maps of all Stokes parameters of 16 spectral features that showed elliptical polarization. The magnitude and direction of the magnetic field have been obtained by the detection of 7 Zeeman pairs. The three dimensional orientation of the magnetic field can be obtained, following the theoretical arguments of Goldreich et. al., from the observation of π and σ components.

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Modelling of form in thermotropic polymers

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1994.0082 ◽

1994 ◽

Vol 348 (1686) ◽

pp. 73-96 ◽

Cited By ~ 5

Keyword(s):

Liquid Crystalline ◽

Main Chain ◽

Three Dimensional ◽

Point Singularity ◽

Dimensional Solution ◽

Crystalline Polymers ◽

Elasticity Equations ◽

Lower Total Energy ◽

Third Dimension ◽

Crystalline Microstructure

A lattice model of liquid crystalline microstructure has been developed. It provides the basis for the three-dimensional solution of the Frank elasticity equations for given boundary conditions while, in addition, providing a mechanistic representation of the development of texture as the microstructure relaxes with time. It is also able to represent disclination motion and the processes associated with their interaction. In particular, it has been used to study (s = ± 1/2) disclination loops, both those described by a single rotation vector, 17, and those in which 17 has a constant angular relationship with the loop line and are equivalent to a point singularity at a distance much larger than the loop radius. The application of the model to disclinations of unit strength, which are unstable both energetically and topologically, has shown that the decomposition into two 1/2 strength lines of lower total energy occurs much more readily than topological escape in the third dimension. The implication for structures observed in capillary tubes is discussed. The influence on microstructure of a splay constant much higher than that of twist or bend is explored in the context of main-chain liquid crystalline polymers, in particular, the stabilization of tangential +1 lines under such conditions is predicted in accord with observed microstructural features.

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INCREASING THE EFFICIENCY OF MULTY-VARIANT CALCULATIONS OF ELECTROMAGNETIC FIELD DISTRIBUTION IN MATRIX OF A POLYGRADIENT SEPARATOR

EUREKA Physics and Engineering ◽

10.21303/2461-4262.2021.001713 ◽

2021 ◽

Author(s):

Jasim Mohmed Jasim Jasim ◽

Iryna Shvedchykova ◽

Igor Panasiuk ◽

Julia Romanchenko ◽

Inna Melkonova

Keyword(s):

Magnetic Field ◽

Field Distribution ◽

Three Dimensional ◽

Magnetic Potential ◽

Geometric Parameters ◽

Two Dimensional ◽

Air Gaps ◽

Vector Magnetic Potential ◽

Electromagnetic Separator ◽

The Magnetic Field

An approach is proposed to carry out multivariate calculations of the magnetic field distribution in the working gaps of a plate polygradient matrix of an electromagnetic separator, based on a combination of the advantages of two- and three-dimensional computer modeling. Two-dimensional geometric models of computational domains are developed, which differ in the geometric dimensions of the plate matrix elements and working air gaps. To determine the vector magnetic potential at the boundaries of two-dimensional computational domains, a computational 3D experiment is carried out. For this, three variants of the electromagnetic separator are selected, which differ in the size of the working air gaps of the polygradient matrices. For them, three-dimensional computer models are built, the spatial distribution of the magnetic field in the working intervals of the electromagnetic separator matrix and the obtained numerical values of the vector magnetic potential at the boundaries of the computational domains are investigated. The determination of the values of the vector magnetic potential for all other models is carried out by interpolation. The obtained values of the vector magnetic potential are used to set the boundary conditions in a computational 2D experiment. An approach to the choice of a rational version of a lamellar matrix is substantiated, which provides a solution to the problem according to the criterion of the effective area of the working area. Using the method of simple enumeration, a variant of the structure of a polygradient matrix with rational geometric parameters is selected. The productivity of the electromagnetic separator with rational geometric parameters of the matrix increased by 3–5 % with the same efficiency of extraction of ferromagnetic inclusions in comparison with the basic version of the device

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