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Your search keyword '"Wermeille, D."' showing total 118 results
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118 results on '"Wermeille, D."'

2. Interaction between U/UO2 bilayers and hydrogen studied by in-situ X-ray diffraction

Author

Darnbrough, J. Ed, Harker, R. M., Griffiths, I, Wermeille, D., Lander, G. H., and Springell, R.

Subjects
Condensed Matter - Materials Science
Abstract

This paper reports experiments investigating the reaction of H$_{2}$ with uranium metal-oxide bilayers. The bilayers consist of $\leq$ 100 nm of epitaxial $\alpha$-U (grown on a Nb buffer deposited on sapphire) with a UO$_{2}$ overlayer of thicknesses of between 20 and 80 nm. The oxides were made either by depositing via reactive magnetron sputtering, or allowing the uranium metal to oxidise in air at room temperature. The bilayers were exposed to hydrogen, with sample temperatures between 80 and 200 C, and monitored via in-situ x-ray diffraction and complimentary experiments conducted using Scanning Transmission Electron Microscopy - Electron Energy Loss Spectroscopy (STEM-EELS). Small partial pressures of H$_{2}$ caused rapid consumption of the U metal and lead to changes in the intensity and position of the diffraction peaks from both the UO$_{2}$ overlayers and the U metal. There is an orientational dependence in the rate of U consumption. From changes in the lattice parameter we deduce that hydrogen enters both the oxide and metal layers, contracting the oxide and expanding the metal. The air-grown oxide overlayers appear to hinder the H$_{2}$-reaction up to a threshold dose, but then on heating from 80 to 140 C the consumption is more rapid than for the as-deposited overlayers. STEM-EELS establishes that the U-hydride layer lies at the oxide-metal interface, and that the initial formation is at defects or grain boundaries, and involves the formation of amorphous and/or nanocrystalline UH$_{3}$. This explains why no diffraction peaks from UH$_{3}$ are observed. {\textcopyright British Crown Owned Copyright 2017/AWE}, Comment: Submitted for peer review

Published
2017
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3. Phase coexistence induced surface roughness in V2O3/Ni magnetic heterostructures.

Author

Ignatova, K., Vlasov, E., Seddon, S. D., Gauquelin, N., Verbeeck, J., Wermeille, D., Bals, S., Hase, T. P. A., and Arnalds, U. B.

Subjects
SURFACE roughness, SCANNING transmission electron microscopy, PHASE transitions, ELECTRON energy loss spectroscopy, HETEROSTRUCTURES, MAGNETIC films, REACTIVE sputtering
Abstract

We present an investigation of the microstructure changes in V2O3 as it goes through its inherent structural phase transition. Using V2O3 films with a well-defined crystal structure deposited by reactive magnetron sputtering on r-plane Al2O3 substrates, we study the phase coexistence region and its impact on the surface roughness of the films and the magnetic properties of overlying Ni magnetic layers in V2O3/Ni hybrid magnetic heterostructures. The simultaneous presence of two phases in V2O3 during its structural phase transition was identified with high resolution x-ray diffraction and led to an increase in surface roughness observed using x-ray reflectivity. The roughness reaches its maximum at the midpoint of the transition. In V2O3/Ni hybrid heterostructures, we find a concomitant increase in the coercivity of the magnetic layer correlated with the increased roughness of the V2O3 surface. The chemical homogeneity of the V2O3 is confirmed through transmission electron microscopy analysis. High-angle annular dark field imaging and electron energy loss spectroscopy reveal an atomically flat interface between Al2O3 and V2O3, as well as a sharp interface between V2O3 and Ni. [ABSTRACT FROM AUTHOR]

Published
2024
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4. The malleability of uranium: manipulating the charge-density wave in epitaxial films

Author

Springell, R., Ward, R. C. C., Bouchet, J., Chivall, J., Wermeille, D., Normile, P. S., Langridge, S., Zochowski, S. W., and Lander, G. H.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract

We report x-ray synchrotron experiments on epitaxial films of uranium, deposited on niobium and tungsten seed layers. Despite similar lattice parameters for these refractory metals, the uranium epitaxial arrangements are different and the strains propagated along the a-axis of the uranium layers are of opposite sign. At low temperatures these changes in epitaxy result in dramatic modifications to the behavior of the charge-density wave in uranium. The differences are explained with the current theory for the electron-phonon coupling in the uranium lattice. Our results emphasize the intriguing possibilities of producing epitaxial films of elements that have complex structures like the light actinides uranium to plutonium., Comment: 6 pages, 6 figures

Published
2014
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5. Antiferromagnetic order and domains in Sr3Ir2O7 probed by x-ray resonant scattering

Author

Boseggia, S., Springell, R., Walker, H. C., Boothroyd, A. T., Prabhakaran, D., Wermeille, D., Bouchenoire, L., Collins, S. P., and McMorrow, D. F.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

This article reports a detailed x-ray resonant scattering study of the bilayer iridate compound, Sr3Ir2O7, at the Ir L2 and L3 edges. Resonant scattering at the Ir L3 edge has been used to determine that Sr3Ir2O7 is a long-range ordered antiferromagnet below TN 230K with an ordering wavevector, q=(1/2,1/2,0). The energy resonance at the L3 edge was found to be a factor of ~30 times larger than that at the L2. This remarkable effect has been seen in the single layer compound Sr2IrO4 and has been linked to the observation of a Jeff=1/2 spin-orbit insulator. Our result shows that despite the modified electronic structure of the bilayer compound, caused by the larger bandwidth, the effect of strong spin-orbit coupling on the resonant magnetic scattering persists. Using the programme SARAh, we have determined that the magnetic order consists of two domains with propagation vectors k1=(1/2,1/2,0) and k2=(1/2,-1/2,0), respectively. A raster measurement of a focussed x-ray beam across the surface of the sample yielded images of domains of the order of 100 microns size, with odd and even L components, respectively. Fully relativistic, monoelectronic calculations (FDMNES), using the Green's function technique for a muffin-tin potential have been employed to calculate the relative intensities of the L2,3 edge resonances, comparing the effects of including spin-orbit coupling and the Hubbard, U, term. A large L3 to L2 edge intensity ratio (~5) was found for calculations including spin-orbit coupling. Adding the Hubbard, U, term resulted in changes to the intensity ratio <5%., Comment: 9 pages, 9 figures

Published
2012
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6. X-ray pushing of a mechanical microswing

Author

Siria, A., Rodrigues, M. S., Dhez, O., Schwartz, W., Torricelli, G., Denmat, S. Le, Rochat, N., Auvert, G., Bikondoa, O., Metzger, T. H., Wermeille, D., Felici, R., Comin, F., and Chevrier, J.

Subjects
Physics - Instrumentation and Detectors
Abstract

Nanoelectromechanical Systems (NEMS) are among the best candidates to measure interactions at nanoscale [1-6], especially when resonating oscillators are used with high quality factor [7, 8]. Despite many efforts [9, 10], efficient and easy actuation in NEMS remains an issue [11]. The mechanism that we propose, thermally mediated Center Of Mass (COM) displacements, represents a new actuation scheme for NEMS and MEMS. To demonstrate this scheme efficiency we show how mechanical nanodis- placements of a MEMS is triggered using modulated X-ray microbeams. The MEMS is a microswing constituted by a Ge microcrystal attached to a Si microcantilever. The interaction is mediated by the Ge absorption of the intensity modulated X-ray microbeam impinging on the microcrystal. The small but finite thermal expansion of the Ge microcrystal is large enough to force a nanodisplacement of the Ge microcrystal COM glued on a Si microlever. The inverse mechanism can be envisaged: MEMS can be used to shape X-ray beams. A Si microlever can be a high frequency X-ray beam chopper for time studies in biology and chemistry., Comment: 5 pages, 4 figure

Published
2008
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7. Distinct order of Gd 4f and Fe 3d moments coexisting in GdFe4Al8

Author

Angst, M., Kreyssig, A., Janssen, Y., Kim, J. -W., Tan, L., Wermeille, D., Mozharivskyij, Y., Kracher, A., Goldman, A. I., and Canfield, P. C.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

Single crystals of flux-grown tetragonal GdFe4Al8 were characterized by thermodynamic, transport, and x-ray resonant magnetic scattering measurements. In addition to antiferromagnetic order at TN ~ 155 K, two low-temperature transitions at T1 ~ 21 K and T2 ~ 27 K were identified. The Fe moments order at TN with an incommensurate propagation vector (tau,tau,0) with tau varying between 0.06 and 0.14 as a function of temperature, and maintain this order over the entire T

Published
2005
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11. REXS contribution to electronic ordering investigation in solids

Author

Beale, T. A. W., Beutier, G., Bland, S. R., Bombardi, A., Bouchenoire, L., Bunău, O., Di Matteo, S., Fernández-Rodríguez, J., Hamann-Borrero, J. E., Herrero-Martín, J., Jacques, V. L. R., Johnson, R. D., Juhin, A., Matsumura, T., Mazzoli, C., Mulders, A. M., Nakao, H., Okamoto, J., Partzsch, S., Princep, A. J., Scagnoli, V., Strempfer, J., Vecchini, C., Wakabayashi, Y., Walker, H. C., Wermeille, D., and Yamasaki, Y.

Published
2012
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12. Structural and magnetic properties of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\lbrack$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\rbrack$\end{document}Er|Tb\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\lbrack$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\rbrack$\end{document}multilayers

Author

Voigt, J., Kentzinger, E., Rücker, U., Schweika, W., Wermeille, D., Schmidt, W., and Brückel, Th.

Published
2006
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15. Structural and magnetic properties of $\lbrack$ErTb$\rbrack$multilayers

Author

Voigt, J., Kentzinger, E., Rücker, U., Schweika, W., Wermeille, D., Schmidt, W., and Brückel, Th

Subjects
Condensed Matter::Materials Science
Abstract

We have investigated the structural and magnetic properties of $\lbrack$ Er|Tb $\rbrack$ multilayers by different scattering methods. Diffuse X-ray scattering under grazing incidence reveals the interface structure in $\lbrack$ Er|Tb $\rbrack$ bilayers and trilayers, indicating vertically correlated roughness between the Er and Tb interfaces. The magnetic properties of $\lbrack$ ErnEr|TbnTb $\rbrack$ superlattices have been studied as a function of the superlattice composition (indices denote the number of atomic layers). Coupled ferromagnetic structures exist in all investigated samples. The phase transition temperature varies with the Tb layer thickness. Modulated magnetic order is short range for all samples beside the $\lbrack$ Er20|Tb5 $\rbrack$ superlattice, the sample with the smallest Tb layer thickness. We observe dipolar antiferromagnetic coupling between single ferromagnetic Tb layers in all samples, with the onset of this ordering depending on the Tb layer thickness. Due to competing interactions, exchange coupling is limited to the interface near region. Therefore long range modulated magnetic order is observed in the $\lbrack$ Er20|Tb5 $\rbrack$ superlattice only, where the interface regions overlap. The distinct differences to the magnetic structure of an Er0.8Tb0.2 alloy film are explained by a highly anisotropic arrangement of neighbouring atoms due to the correlated roughness

Published
2018

16. Measurements related to the magnetism of curium metal

Author

Lander, G. H., primary, Griveau, J.-C., additional, Eloirdi, R., additional, Magnani, N., additional, Colineau, E., additional, Wilhelm, F., additional, Brown, S. D., additional, Wermeille, D., additional, Rogalev, A., additional, Haire, R. G., additional, and Caciuffo, R., additional

Published
2019
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18. Antiferromagnetic order and domains in Sr3Ir2O7 probed by x-ray resonant scattering

Author

Boseggia, S, Springell, R, Walker, HC, Boothroyd, AT, Prabhakaran, D, Wermeille, D, Bouchenoire, L, Collins, SP, and McMorrow, DF

Subjects
Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences
Abstract

This article reports a detailed x-ray resonant scattering study of the bilayer iridate compound, Sr3Ir2O7, at the Ir L2 and L3 edges. Resonant scattering at the Ir L3 edge has been used to determine that Sr3Ir2O7 is a long-range ordered antiferromagnet below TN 230K with an ordering wavevector, q=(1/2,1/2,0). The energy resonance at the L3 edge was found to be a factor of ~30 times larger than that at the L2. This remarkable effect has been seen in the single layer compound Sr2IrO4 and has been linked to the observation of a Jeff=1/2 spin-orbit insulator. Our result shows that despite the modified electronic structure of the bilayer compound, caused by the larger bandwidth, the effect of strong spin-orbit coupling on the resonant magnetic scattering persists. Using the programme SARAh, we have determined that the magnetic order consists of two domains with propagation vectors k1=(1/2,1/2,0) and k2=(1/2,-1/2,0), respectively. A raster measurement of a focussed x-ray beam across the surface of the sample yielded images of domains of the order of 100 microns size, with odd and even L components, respectively. Fully relativistic, monoelectronic calculations (FDMNES), using the Green's function technique for a muffin-tin potential have been employed to calculate the relative intensities of the L2,3 edge resonances, comparing the effects of including spin-orbit coupling and the Hubbard, U, term. A large L3 to L2 edge intensity ratio (~5) was found for calculations including spin-orbit coupling. Adding the Hubbard, U, term resulted in changes to the intensity ratio, 9 pages, 9 figures

Published
2016

19. Determination of the Poisson ratio of (001) and (111) oriented thin films of In2O3 by synchrotron-based x-ray diffraction

Author

Zhang, K H L, Regoutz, A, Palgrave, R G, Payne, D J, Egdell, R G, Walsh, Aron, Collins, S P, Wermeille, D, and Cowley, R A

Subjects
Condensed Matter::Materials Science
Abstract

The Poisson ratio ν of In 2O 3 has been determined by measurement of the covariation of in-plane and out-of-plane lattice parameters of strained thin films grown epitaxially on (111) and (001) oriented cubic Y-stabilized ZrO 2 substrates. The experimental results are in good agreement with values for ν calculated using atomistic simulation procedures. © 2011 American Physical Society.

Published
2016

20. X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in gamma-Al2O3

Author

Thompson, PBJ, Nguyen, BN, Nicholls, R, Bourne, RA, Brazier, JB, Lovelock, KRJ, Brown, SD, Wermeille, D, Bikondoa, O, Lucas, CA, Hase, TPA, and Newton, MA

Abstract

The 2-4 keV energy range provides a rich window into many facets of materials science and chemistry. Within this window, P, S, Cl, K and Ca K-edges may be found along with the L-edges of industrially important elements from Y through to Sn. Yet, compared with those that cater for energies above ca. 4-5 keV, there are relatively few resources available for X-ray spectroscopy below these energies. In addition, in situ or operando studies become to varying degrees more challenging than at higher X-ray energies due to restrictions imposed by the lower energies of the X-rays upon the design and construction of appropriate sample environments. The XMaS beamline at the ESRF has recently made efforts to extend its operational energy range to include this softer end of the X-ray spectrum. In this report the resulting performance of this resource for X-ray spectroscopy is detailed with specific attention drawn to: understanding electrostatic and charge transfer effects at the S K-edge in ionic liquids; quantification of dilution limits at the Cl K- and Rh L3-edges and structural equilibria in solution; in vacuum deposition and reduction of [RhI(CO)2Cl]2 to [gamma]-Al2O3; contamination of [gamma]-Al2O3 by Cl and its potential role in determining the chemical character of supported Rh catalysts; and the development of chlorinated Pd catalysts in `green' solvent systems. Sample environments thus far developed are also presented, characterized and their overall performance evaluated.

Published
2015

22. Simultaneous dynamic electrical and structural measurements of functional materials

Author

Vecchini, C., primary, Thompson, P., additional, Stewart, M., additional, Muñiz-Piniella, A., additional, McMitchell, S. R. C., additional, Wooldridge, J., additional, Lepadatu, S., additional, Bouchenoire, L., additional, Brown, S., additional, Wermeille, D., additional, Bikondoa, O., additional, Lucas, C. A., additional, Hase, T. P. A., additional, Lesourd, M., additional, Dontsov, D., additional, and Cain, M. G., additional

Published
2015
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27. $\mathrm{K}$-edge resonant x-ray magnetic scattering from $\mathrm{RbMnF_3}$

Author

Stunault, A., De Bergevin, F., Wermeille, D., Vettier, C., Brückel, Th., Bernhoeft, N., McIntyre, G. J., and Henry, J. Y.

Subjects
ddc:530
Abstract

Physical review / B 60(14), 10170 - 10179 (1999). doi:10.1103/PhysRevB.60.10170, Magnetic resonant x-ray scattering experiments at the MnK edge have revealed the occurrence of two different resonances in antiferromagnetic RbMnF3. Below the K edge, at the 3d threshold, the resonance profile is consistent with quadrupole electrical transitions from the 1s core level to the 3dstates; the observed resonance amplitude corresponds to the expected value for spin-orbit splitting in 3d levels. The resonance at the 4p threshold extends over the whole 4p band; it is explained on the basis of electric dipole transitions which involve both spin-orbit splitting and exchange splitting of the 4pstates., Published by Inst., Woodbury, NY

Published
1999

33. Ultrahigh vacuum/high-pressure flow reactor for surface x-ray diffraction and grazing incidence small angle x-ray scattering studies close to conditions for industrial catalysis

Author

van Rijn, R., primary, Ackermann, M. D., additional, Balmes, O., additional, Dufrane, T., additional, Geluk, A., additional, Gonzalez, H., additional, Isern, H., additional, de Kuyper, E., additional, Petit, L., additional, Sole, V. A., additional, Wermeille, D., additional, Felici, R., additional, and Frenken, J. W. M., additional

Published
2010
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36. X-ray pushing of a mechanical microswing

Author

Siria, A, primary, Rodrigues, M S, additional, Dhez, O, additional, Schwartz, W, additional, Torricelli, G, additional, LeDenmat, S, additional, Rochat, N, additional, Auvert, G, additional, Bikondoa, O, additional, Metzger, T H, additional, Wermeille, D, additional, Felici, R, additional, Comin, F, additional, and Chevrier, J, additional

Published
2008
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37. Non-Resonant and Resonant X-Ray Scattering Studies on MultiferroicTbMn2O5

Author

Koo, J., primary, Song, C., additional, Ji, S., additional, Lee, J.-S., additional, Park, J., additional, Jang, T.-H., additional, Yang, C.-H., additional, Park, J.-H., additional, Jeong, Y. H., additional, Lee, K.-B., additional, Koo, T. Y., additional, Park, Y. J., additional, Kim, J.-Y., additional, Wermeille, D., additional, Goldman, A. I., additional, Srajer, G., additional, Park, S., additional, and Cheong, S.-W., additional

Published
2007
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44. Magnetic structure ofGdCo2Ge2

Author

Good, W., primary, Kim, J., additional, Goldman, A., additional, Wermeille, D., additional, Canfield, P., additional, Cunningham, C., additional, Islam, Z., additional, Lang, J., additional, Srajer, G., additional, and Fisher, I., additional

Published
2005
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45. Magnetic structure ofGd5Ge4

Author

Tan, L., primary, Kreyssig, A., additional, Kim, J. W., additional, Goldman, A. I., additional, McQueeney, R. J., additional, Wermeille, D., additional, Sieve, B., additional, Lograsso, T. A., additional, Schlagel, D. L., additional, Budko, S. L., additional, Pecharsky, V. K., additional, and Gschneidner, K. A., additional

Published
2005
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50. X-ray magnetic circular dichroism study ofTbNi2B2C

Author

Song, C., primary, Lang, J. C., additional, Detlefs, C., additional, Létoublon, A., additional, Good, W., additional, Kim, J., additional, Wermeille, D., additional, Bud’ko, S. L., additional, Canfield, P. C., additional, and Goldman, A. I., additional

Published
2001
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