scholarly journals On the possibility of using X-ray Compton scattering to study magnetoelectrical properties of crystals

2016 ◽  
Vol 72 (2) ◽  
pp. 197-205 ◽  
Author(s):  
S. P. Collins ◽  
D. Laundy ◽  
T. Connolley ◽  
G. van der Laan ◽  
F. Fabrizi ◽  
...  
Keyword(s):  
Compton Scattering ◽  
First Principles ◽  
Momentum Density ◽  
Orbit Interaction ◽  
Compton Profile ◽  
X Ray ◽  
X Ray Scattering ◽  
Crystallographic Symmetry ◽  
Order Of Magnitude ◽  
Antisymmetric Component

This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and the first experimental results are shown, on a single-domain crystal of GaFeO3. The measured antisymmetric Compton profile is very small (≃ 10−5of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample.

scholarly journals Process Induced Skin-Core Morphology in Injection Molded Polyamide 66

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 894
Author(s):  
Yvonne Spoerer ◽  
René Androsch ◽  
Dieter Jehnichen ◽  
Ines Kuehnert
Keyword(s):  
Polarized Light ◽  
Skin Layer ◽  
Crystalline Morphology ◽  
Polyamide 66 ◽  
Thin Sections ◽  
X Ray ◽  
X Ray Scattering ◽  
Order Of Magnitude ◽  
Injection Molded ◽  
Ray Scattering

Polyamide 66 (PA 66) was injection-molded to obtain samples with a structure gradient between skin and core, as it was revealed by analysis of the semi-crystalline morphology using polarized-light optical microscopy (POM). Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) were employed to characterize thin sections with a thickness in the order of magnitude of 50 µm, allowing detection of crystals of different perfection, as a function of the distance from the surface. It was found that the transparent and non-spherulitic skin layer contains rather imperfect α-crystals while the perfection of α-crystals continuously increases with extending distance from the surface. Since variation of the molding conditions allows tailoring the skin-core morphology, the present study was performed to suggest a reliable route to map the presence of specific semi-crystalline morphologies in such samples.

Influence of molecular structure on the dynamic thermoelasticity of polyphasic polymer systems

1985 ◽  
Vol 63 (1) ◽  
pp. 189-195
Author(s):  
Robert H. Marchessault ◽  
Terry L. Bluhm ◽  
Hrire M. Gharapetian ◽  
Pudupadi R. Sundararajan
Keyword(s):  
Dimethyl Formamide ◽  
Polymer Systems ◽  
X Ray ◽  
X Ray Scattering ◽  
Order Of Magnitude ◽  
Spherical Structures ◽  
Thermoelastic Response ◽  
Heat Pulses ◽  
Molecular Morphology ◽  
The Relationship

The relationship between the dynamic thermoelastic behavior and molecular morphology of polyphasic polymer systems was studied. A sensitive tensometer equipped with a 50 W/I2 V heating lamp provided uniform and controlled heat pulses to one side of the film. For various extension ratios, the stress change (Δσ) as a function of the sample temperature, was recorded, both for increasing and decreasing extension ratios.The amount of increase in stress Δσ with temperature was different for Kraton GX-6500 samples cast from either toluene, cyclohexane, or heptane. The variation of Act with temperature was dependent on the extension ratio and was always greater for increasing extension. The slope of Δσ with temperature decreased at 100–150% elongation in all Kraton GX-6500 samples during increasing extension. However, this slope increased at higher elongations. Small angle X-ray scattering studies on Kraton GX-6500 showed the presence of lamellar, rod shape, and spherical structures in samples cast from toluene, cyclohexane, and heptane solvents, respectively. The extreme dependence of elastomeric behavior on polyphasic morphology caused Kraton samples to show a strong decline in thermoelastic response with cycling.X-ray studies on the films of Spandex, cast from dimethyl formamide, at different extension ratios showed the onset of crystallization at about 150% elongation. The thermoelastic studies performed on Spandex films also showed an increase in slope of Δσ vs. T at 150–170% elongations, which was attributed to the influence of increased crystalline orientation on thermoelastic response. X-ray studies on unstretched and stretched Hytrel films showed the presence of crystallinity. The magnitude of Δσ and variation with temperature for Hytrel films was greater than that of either Spandex, Kraton GX-6500, or cross-linked natural rubber.By comparison with the latter, only Hytrel was superior in the magnitude of Δσ variations with temperature. This was attributed to intrinsic crystallinity and the orientation which developed on stretching. At extension ratios λ = 2, Δσ for Hytrel was an order of magnitude greater than for cross-linked natural rubber.

scholarly journals Anti-symmetric Compton scattering in LiNiPO4: Towards a direct probe of the magneto-electric multipole moment

2021 ◽  
Vol 1 ◽  
pp. 132
Author(s):  
Sayantika Bhowal ◽  
Daniel O'Neill ◽  
Michael Fechner ◽  
Nicola A. Spaldin ◽  
Urs Staub ◽  
...  
Keyword(s):  
Compton Scattering ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Theoretical Work ◽  
Multipole Moment ◽  
Compton Profile ◽  
Magnetoelectric Materials ◽  
Order Of Magnitude ◽  
The Difference ◽  
Electric Multipole Moment

Background: Magnetoelectric multipoles, which break both space-inversion and time-reversal symmetries, play an important role in the magnetoelectric response of a material. Motivated by uncovering the underlying fundamental physics of the magnetoelectric multipoles and the possible technological applications of magnetoelectric materials, understanding as well as detecting such magnetoelectric multipoles has become an active area of research in condensed matter physics. Here we employ the well-established Compton scattering effect as a possible probe for the magnetoelectric toroidal moments in LiNiPO4. Methods: We employ combined theoretical and experimental techniques to compute as well as detect the antisymmetric Compton profile in LiNiPO4. For the theoretical investigation we use density functional theory to compute the anti-symmetric part of the Compton profile for the magnetic and structural ground state of LiNiPO4. For the experimental verification, we measure the Compton signals for a single magnetoelectric domain sample of LiNiPO4, and then again for the same sample with its magnetoelectric domain reversed. We then take the difference between these two measured signals to extract the antisymmetric Compton profile in LiNiPO4. Results: Our theoretical calculations indicate an antisymmetric Compton profile in the direction of the ty toroidal moment in momentum space, with the computed antisymmetric profile around four orders of magnitude smaller than the total profile. The difference signal that we measure is consistent with the computed profile, but of the same order of magnitude as the statistical errors and systematic uncertainties of the experiment. Conclusions: While the weak difference signal in the measurements prevents an unambiguous determination of the antisymmetric Compton profile in LiNiPO4, our results motivate  further theoretical work to understand the factors that influence the size of the antisymmetric Compton profile, and to identify materials exhibiting larger effects.

Local environment of arsenic in sulfide minerals: insights from high-resolution X-ray spectroscopies, and first-principles calculations at the As K-edge

2018 ◽  
Vol 33 (12) ◽  
pp. 2070-2082 ◽  
Author(s):  
Le Pape Pierre ◽  
Blanchard Marc ◽  
Juhin Amélie ◽  
Rueff Jean-Pascal ◽  
Ducher Manoj ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Resolution ◽  
First Principles ◽  
Local Environment ◽  
High Energy ◽  
Sulfide Minerals ◽  
High Energy Resolution ◽  
First Principles Calculations ◽  
X Ray ◽  
X Ray Scattering

To improve our knowledge of arsenic local environment in sulfide minerals, Resonant Inelastic X-Ray Scattering (RIXS) maps and High-Energy Resolution Fluorescence Detected (HERFD) XANES measurements are performed at the As K-edge. In addition, the spectra are compared to XANES modelled through first-principles calculations.

Magnetic Compton Scattering Study of Ni2Mn1.4Sn0.6 Shape Memory Alloy

2013 ◽  
Vol 665 ◽  
pp. 189-193 ◽  
Author(s):  
Alpa Dashora ◽  
H.S. Mund ◽  
J. Sahariya ◽  
K.R. Priolkar ◽  
N. Lobo ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Compton Scattering ◽  
Magnetic Moments ◽  
Momentum Density ◽  
Compton Profile ◽  
Spin Moment ◽  
Scattering Study ◽  
Stoichiometric Alloy ◽  
Spin Momentum

Spin momentum density in Ni2Mn1.4Sn0.6 shape memory alloy has been measured using magnetic Compton scattering technique. The experiment has been performed using 182 keV circularly polarized synchrotron radiation at temperature 10 K at SPring-8, Japan. Experimental magnetic Compton profile has been decomposed to determine the site specific magnetic moments, where the magnetic moment at Mn site was found to be dominating. It is seen that the total spin moment in present non-stoichiometric alloy is smaller than that of stoichiometric Ni2MnSn.

Inelastic X-ray scattering and first-principles study of electron excitations in MgB2

2009 ◽  
Vol 149 (39-40) ◽  
pp. 1706-1711 ◽  
Author(s):  
G. Stutz ◽  
V.M. Silkin ◽  
G. Tirao ◽  
A. Balassis ◽  
E.V. Chulkov ◽  
...  
Keyword(s):  
First Principles ◽  
X Ray ◽  
First Principles Study ◽  
X Ray Scattering ◽  
Electron Excitations ◽  
Ray Scattering

X-ray scattering from a thickness-modulated phase of lipid membranes

2019 ◽  
Vol 52 (2) ◽  
pp. 440-444
Author(s):  
S. Madhukar ◽  
V. A. Raghunathan
Keyword(s):  
Lipid Membranes ◽  
Structural Parameters ◽  
Membrane Thickness ◽  
X Ray ◽  
X Ray Scattering ◽  
Least Squares Fit ◽  
Order Of Magnitude ◽  
Modulated Phase ◽  
Analytical Expressions ◽  
Ray Scattering

An electron density model for small-angle X-ray scattering from a novel thickness-modulated phase of lipid membranes is presented, and analytical expressions are derived for the intensities of the diffraction peaks. Structural parameters of the membranes in this phase have been determined from a least-squares fit of the calculated intensities to the observed ones. The amplitude of the thickness modulation is found to be about an order of magnitude smaller than the membrane thickness, which accounts for the very small number and very weak intensities of the peaks arising from these modulations.

Quantitative treatment for extracting coherent elastic scattering from X-ray scattering experiments

1999 ◽  
Vol 32 (2) ◽  
pp. 322-326 ◽  
Author(s):  
Khalid Laaziri ◽  
J. L. Robertson ◽  
S. Roorda ◽  
M. Chicoine ◽  
S. Kycia ◽  
...  
Keyword(s):  
Impulse Approximation ◽  
Coherent Scattering ◽  
High Energy ◽  
Compton Profile ◽  
Detector Resolution ◽  
X Ray ◽  
Hartree Fock ◽  
Fitting Procedure ◽  
X Ray Scattering ◽  
Peak Function

A fitting procedure for separating the inelastic and elastic contributions to the total scattering in diffuse-scattering experiments at high energy using energy-dispersive X-ray techniques is presented. An asymmetric peak function is used to model the elastic peak. The inelastic scattering peak is modeled using a theoretical Compton profile, calculated using the impulse approximation (Hartree–Fock wave functions were used), convoluted with the detector resolution. This procedure, which requires only two free parameters, is shown to be extremely effective in extracting the integrated elastic intensity of coherent scattering at each wave vector, even at low scattering angles where the Compton scattering is not well resolved.

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