The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies

Brown, S. D.; Bouchenoire, Laurence; Bowyer, D.; Kervin, J.; Laundy, D.; Longfield, M. J.; Mannix, D.; Paul, Daniel; Stunault, A.; Thompson, Paul; Cooper, Malcolm; Lucas, C. A.; Stirling, W. G.

doi:10.1107/s0909049501015394

Cited by 93 publications

(71 citation statements)

References 11 publications

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“…The experiments were mostly carried out at beamline BM28 (XMaS), European Synchrotron Radiation Facility 27 , with preliminary investigations of the pure magnetic and pure resonant scattering carried out at beamline I16, Diamond Light Source 28 (see Supplementary Information). Both beamlines provide intense X-ray beams covering the required energy range (≈7 keV), focussed onto a 10-800 K cryofurnace, mounted at the centre of large six-circle diffractometers.…”

Section: Methodsmentioning

confidence: 99%

“…Both beamlines provide intense X-ray beams covering the required energy range (≈7 keV), focussed onto a 10-800 K cryofurnace, mounted at the centre of large six-circle diffractometers. The sample-a single crystal of FeBO 3 ∼ 4 × 3 × 0.05 mm 3 in size-was attached with its 001 surface normal to the diffractometer φ rotation axis 27 , which was parallel to the azimuthal rotation axis, ψ (Fig. 2).…”

Section: Methodsmentioning

confidence: 99%

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Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

et al. 2014

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Magnetism-the spontaneous alignment of atomic moments in a material-is driven by quantum mechanical exchange interactions that operate over interatomic distances. Some magnetic interactions cause 1,2 , or are caused by 3,4 , a twisting of arrangements of atoms. This can lead to the magnetoelectric e ect, predicted to play a prominent role in future technology, and to the phenomenon of weak ferromagnetism, governed by the so-called Dzyaloshinskii-Moriya interaction 5-8 . Here we determine the sign of the latter interaction in iron borate (FeBO 3 ) by using synchrotron radiation. We present a novel experimental technique based on the interference between two X-ray scattering processes, where one acts as a reference wave. Our experimental results are validated by state-ofthe-art ab initio calculations. Together, our experimental and theoretical approaches are expected to open up new possibilities for exploring, modelling and exploiting novel magnetic and magnetoelectric materials.There is considerable mystery behind the origins of complicated structures. Although the dominant short-range interactions that allow the building blocks to grow are well understood, the much more subtle forces that lead to a particular twisting at larger lengthscales, such as chiral biological molecules and liquid crystals 9 , and canted magnetic systems 3 , remain subjects of topical debate. In this Letter we seek to address this question for the case of magnetism. Our main findings are twofold: first, we demonstrate a novel and elegant experimental method for exploring magnetic materials with weak relativistic spin-orbit interactions, and second, we present a state-of-the-art quantum-mechanical many-body approach to the detailed description of such interactions in crystals. As a touchstone example we selected crystalline iron borate (FeBO 3 ), which is a strongly correlated electron system with a relatively simple crystal structure, nonetheless allowing a nontrivial canted and locally twisted magnetic ordering pattern. Taken together, these two strands demonstrate that modern condensed matter theory is capable of determining the elusive sign of the Dzyaloshinskii-Moriya interaction, and is thus able to elucidate the mechanism for coupling electric and magnetic degrees of freedom in magnetoelectric multiferroics, and to begin to predict the properties of this important class of materials.The interactions between atomic magnetic moments (or spins) are not direct, but mediated by the intervening matter. Coupling can be diminished through screening 10 , or enhanced, for example, by superexchange via oxygen atoms 11 . Moreover, the coupling is a property of the material and, according to Neumann's principle, must therefore possess all of its symmetries. The most general form of the bilinear coupling energy between two spins contains a scalar (isotropic) exchange term, exchange anisotropy (which we will neglect for the present discussion) and an antisymmetric term that reverses with permutation of the spin indices. The latter is the Dzyaloshi...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

et al. 2014

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“…The instrumental function was found to be negligible. The phi scans ͓the angle between the incident beam and z axis in the ͑0yz͒ plane͔ were performed at the XMaS beamline 24 at the ESRF ͑France͒ using a similar GIXD geometry, beam size, and incident angle as at HASYLAB. The GIXD data were measured using a MarCCD detector and normalized using an ionization chamber.…”

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confidence: 99%

Influence of star-like iridium complexes in the graphoepitaxy of polyfluorene thin films

et al. 2006

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We report on the impact on the equatorial and meridional orientation in hairy-rod poly͓9,9-bis͑2-ethylhexyl͒-fluorene-2,7-diyl͔ thin films when blended with tris-cyclometalated oligo-fluorenylpyridine iridium͑III͒ complex. The presence of this transition-metal complex does not alter the underlying helical motif of the polymer chain or the hexagonal unit-cell intermolecular packing. However, systematic changes in the resulting texture patterning of the crystallites are observed. Crystallites with two preferred a-b orientations, so called type I and II and differing by 30 degrees, are superimposed on an isotropic background that is designated as type III. The extent of meridional alignment for all three is found to be similar. DOI: 10.1103/PhysRevB.74.214203 PACS number͑s͒: 61.10.Ϫi, 82.35.Lr, 81.07.Bc, 81.16.Dn Manipulating and controlling the molecular-level structure of functionalized polymers in bulk and at surfaces is central to the science and applications of these materials. Hairy-rod polymers 1 are one important example and, among those with -conjugated backbones 2 ͓e.g., poly͑p-phenylenes͒, 3 polyfluorenes ͑PFs͒, 4 and ladder derivatives 5 ͔, the nature of the main chain conformation and interchain packing are crucial factors in ultimately determining optical and transport properties. The structural characteristics at larger length scales are equally as important, and this has been the main emphasis in a number of recent studies. A classic example is the poly͑3-alkylthiophene͒ family 6 in which the extent of structural isomorphism or regioregularity strongly affects the internal crystallite structure 7 and the subsequent structural evolution when intercalated or doped. 8 Among PFs, important blue emitting polymers, even small differences in the molecular structure can influence the charge carrier mobility 9 and fluorescence. 10 Poly͓9,9-bis͑2-ethylhexyl͒-9H-fluorene-2,7-diyl͔ ͑or PF2/6͒ ͑Ref. 11͒ is a well-known helical PF polymer functionalized with branched alkyl side chains. PF2/6's optical properties 12 are relatively insensitive to either changes in the molecular weight ͑MW͒ or processing history, and so it is an excellent model system for studies of intermolecular self-organization. 13 However, this intermolecular assembly is affected by changes in the MW ͑or number averaged MW, M n ͒. In PF2/6, there is a threshold MW, M n * , at which there is a crossover in the phase behavior. 14 Low MW samples exhibit only a single nematic liquid crystal phase ͑n-LC and M n Ͻ M n * ͒ while high MW samples ͑M n Ͼ M n * ͒ include a distinctive thermotropic transition between this n-LC phase and a hexagonal crystalline phase. This threshold MW also marks sharp changes in both meridional alignment 15 and surface morphology. 16 In aligned films on rubbed polyimide ͑PI͒, the rigid PF2/6 lies on the substrate with the helical axes pointing along the rubbing direction ͑denoted z here͒. Consequently, meridional alignment leads to a large absorption and dispersion of the refractive index in the ͑xy0͒ plane along the z...

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“…The non resonant magnetic diffraction experiment was performed on the XMaS beamline [9] at ESRF. Elliptically polarized radiation was extracted by viewing the bending magnet source at a angle of ≈ 0.3mrad from the plane of the synchrotron: the optimum position in terms of signal to noise.…”

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Temperature dependence of the spin and orbital magnetization density inSm0.982Gd0.018Al
Taylor
¹
,
Duffy
²
,
Bebb
³

et al. 2002
Phys. Rev. B
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Non-resonant ferromagnetic x-ray diffraction has been used to separate the spin and orbital contribution to the magnetization density of the proposed zero-moment ferromagnet Sm0.982Gd0.018Al2. The alignment of the spin and orbital moments relative to the net magnetization shows a sign reversal at 84K, the compensation temperature. Below this temperature the orbital moment is larger than the spin moment, and vice versa above it. This result implies that the compensation mechanism is driven by the different temperature dependencies of the 4f spin and orbital moments. Specific heat data indicate that the system remains ferromagnetically ordered throughout.

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The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies

Cited by 93 publications

References 11 publications

Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

Influence of star-like iridium complexes in the graphoepitaxy of polyfluorene thin films

Temperature dependence of the spin and orbital magnetization density inSm0.982Gd0.018Al
Taylor
¹
,
Duffy
²
,
Bebb
³

et al. 2002
Phys. Rev. B
Self Cite
43
4
36
0
View full text Add to dashboard Cite

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The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies

Cited by 93 publications

References 11 publications

Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

Measuring the Dzyaloshinskii–Moriya interaction in a weak ferromagnet

Influence of star-like iridium complexes in the graphoepitaxy of polyfluorene thin films

Temperature dependence of the spin and orbital magnetization density inSm0.982Gd0.018AlTaylor1, Duffy2, Bebb3 et al. 2002Phys. Rev. BSelf Cite434360View full textAdd to dashboardCite

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Temperature dependence of the spin and orbital magnetization density inSm0.982Gd0.018Al
Taylor
¹
,
Duffy
²
,
Bebb
³

et al. 2002
Phys. Rev. B
Self Cite
43
4
36
0
View full text Add to dashboard Cite