I10-Beamline for Advanced Dichroism - scattering
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Xiaodong
Xie
,
Kejing
Ran
,
Yizhou
Liu
,
Raymond
Fan
,
Wancong
Tan
,
Haonan
Jin
,
Manuel
Valvidares
,
Nicolas
Jaouen
,
Haifeng
Du
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Shilei
Zhang
Diamond Proposal Number(s):
[20437, 26148, 22629]
Abstract: We identify a three-dimensional skyrmion side-face state in chiral magnets that consists of a thin layer of modulated surface spirals and an array of phase-locked skyrmion screws. Such chiral spin structures lead to a characteristic X-shaped magnetic diffraction pattern in resonant elastic x-ray scattering, reminiscent of Photo 51 of the DNA double-helix diffraction. By measuring both thin plates and bulk
Cu
2
OSeO
3
crystals in the field-in-plane geometry, we unambiguously identify the modulated skyrmion strings by retrieving their chirality and helix angle. The breaking of the translational symmetry along the side faces suppresses the bulk-favored conical state, providing a stabilization mechanism for the skyrmion lattice phase that has been overlooked so far.
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Feb 2023
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Nanna
Zhou Hagström
,
Michael
Schneider
,
Nico
Kerber
,
Alexander
Yaroslavtsev
,
Erick
Burgos Parra
,
Marijan
Beg
,
Martin
Lang
,
Christian M.
Günther
,
Boris
Seng
,
Fabian
Kammerbauer
,
Horia
Popescu
,
Matteo
Pancaldi
,
Kumar
Neeraj
,
Debanjan
Polley
,
Rahul
Jangid
,
Stjepan B.
Hrkac
,
Sheena K. K.
Patel
,
Sergei
Ovcharenko
,
Diego
Turenne
,
Dmitriy
Ksenzov
,
Christine
Boeglin
,
Marina
Baidakova
,
Clemens
Von Korff Schmising
,
Martin
Borchert
,
Boris
Vodungbo
,
Kai
Chen
,
Chen
Luo
,
Florin
Radu
,
Leonard
Müller
,
Miriam
Martínez Flórez
,
André
Philippi-Kobs
,
Matthias
Riepp
,
Wojciech
Roseker
,
Gerhard
Grübel
,
Robert
Carley
,
Justine
Schlappa
,
Benjamin E.
Van Kuiken
,
Rafael
Gort
,
Laurent
Mercadier
,
Naman
Agarwal
,
Loïc
Le Guyader
,
Giuseppe
Mercurio
,
Martin
Teichmann
,
Jan Torben
Delitz
,
Alexander
Reich
,
Carsten
Broers
,
David
Hickin
,
Carsten
Deiter
,
James
Moore
,
Dimitrios
Rompotis
,
Jinxiong
Wang
,
Daniel
Kane
,
Sandhya
Venkatesan
,
Joachim
Meier
,
Florent
Pallas
,
Tomasz
Jezynski
,
Maximilian
Lederer
,
Djelloul
Boukhelef
,
Janusz
Szuba
,
Krzysztof
Wrona
,
Steffen
Hauf
,
Jun
Zhu
,
Martin
Bergemann
,
Ebad
Kamil
,
Thomas
Kluyver
,
Robert
Rosca
,
Michał
Spirzewski
,
Markus
Kuster
,
Monica
Turcato
,
David
Lomidze
,
Andrey
Samartsev
,
Jan
Engelke
,
Matteo
Porro
,
Stefano
Maffessanti
,
Karsten
Hansen
,
Florian
Erdinger
,
Peter
Fischer
,
Carlo
Fiorini
,
Andrea
Castoldi
,
Massimo
Manghisoni
,
Cornelia Beatrix
Wunderer
,
Eric E.
Fullerton
,
Oleg G.
Shpyrko
,
Christian
Gutt
,
Cecilia
Sanchez-Hanke
,
Hermann A.
Dürr
,
Ezio
Iacocca
,
Hans T.
Nembach
,
Mark W.
Keller
,
Justin M.
Shaw
,
Thomas J.
Silva
,
Roopali
Kukreja
,
Hans
Fangohr
,
Stefan
Eisebitt
,
Mathias
Kläui
,
Nicolas
Jaouen
,
Andreas
Scherz
,
Stefano
Bonetti
,
Emmanuelle
Jal
Open Access
Abstract: The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers access to X-rays with unprecedented brightness, coherence and pulse duration. All XFEL facilities built until recently provided X-ray pulses at a relatively low repetition rate, with limited data statistics. Here, results from the first megahertz-repetition-rate X-ray scattering experiments at the Spectroscopy and Coherent Scattering (SCS) instrument of the European XFEL are presented. The experimental capabilities that the SCS instrument offers, resulting from the operation at megahertz repetition rates and the availability of the novel DSSC 2D imaging detector, are illustrated. Time-resolved magnetic X-ray scattering and holographic imaging experiments in solid state samples were chosen as representative, providing an ideal test-bed for operation at megahertz rates. Our results are relevant and applicable to any other non-destructive XFEL experiments in the soft X-ray range.
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Nov 2022
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[27196]
Abstract: Isotropic helimagnets are known to host a diverse range of chiral magnetic states. In 2016, Rybakov et al., theorized the presence of a surface-pinned stacked spin spiral phase [F. N. Rybakov et al., New J. Phys. 18, 045002 (2016)], which has yet to be observed experimentally. The phase is characterized by surface spiral periods exceeding the host material's fundamental winding period
L
D
. Here, we present experimental evidence for the observation of this state in lamellae of FeGe using resonant x-ray holographic imaging data and micromagnetic simulations. We find images of FeGe lamellae, exceeding a critical thickness of 300 nm (
4.3
L
D
), exhibit contrast modulations with a field-dependent periodicity of
λ
≥
1.4
L
D
, consistent with theoretical predictions of the stacked spiral state. The identification of this spiral state has significant implications for the stability of other coexisting spin textures, and will help complete our understanding of helimagnetic systems.
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Aug 2022
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Cyril
Leveille
,
Erick
Burgos-Parra
,
Yanis
Sassi
,
Fernando
Ajejas
,
Valentin
Chardonnet
,
Emanuele
Pedersoli
,
Flavio
Capotondi
,
Giovanni
De Ninno
,
Francesco
Maccherozzi
,
Sarnjeet
Dhesi
,
David M.
Burn
,
Gerrit
Van Der Laan
,
Oliver S.
Latcham
,
Andrey V.
Shytov
,
Volodymyr V.
Kruglyak
,
Emmanuelle
Jal
,
Vincent
Cros
,
Jean-Yves
Chauleau
,
Nicolas
Reyren
,
Michel
Viret
,
Nicolas
Jaouen
Open Access
Abstract: Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows for the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions among others. We report here on the behavior of chiral DWs at ultrashort timescale after optical pumping in perpendicularly magnetized asymmetric multilayers. The magnetization dynamics is probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously varying spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of spins from the interior of the neighboring magnetic domains. We identify this time-varying change of the DW texture shortly after the laser pulse as a distortion of the homochiral Néel shape toward a transient mixed Bloch-Néel-Bloch texture along a direction transverse to the DW.
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Mar 2022
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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C. D.
Dashwood
,
A.
Geondzhian
,
J. G.
Vale
,
A. C.
Pakpour-Tabrizi
,
C. A.
Howard
,
Q.
Faure
,
L. S. I.
Veiga
,
D.
Meyers
,
G. S.
Chiuzbaian
,
A.
Nicolaou
,
N.
Jaouen
,
R. B.
Jackman
,
A.
Nag
,
M.
Garcia-Fernandez
,
Ke-Jin
Zhou
,
A. C.
Walters
,
K.
Gilmore
,
D. F.
Mcmorrow
,
M. P. M.
Dean
Diamond Proposal Number(s):
[22695]
Open Access
Abstract: Interactions between electrons and lattice vibrations are responsible for a wide range of material properties and applications. Recently, there has been considerable interest in the development of resonant inelastic x-ray scattering (RIXS) as a tool for measuring electron-phonon (
e
-ph) interactions. Here, we demonstrate the ability of RIXS to probe the interaction between phonons and specific electronic states both near to, and away from, the Fermi level. We perform carbon
K
-edge RIXS measurements on graphite, tuning the incident x-ray energy to separately probe the interactions of the
π
∗
and
σ
∗
electronic states. Our high-resolution data reveal detailed structure in the multiphonon RIXS features that directly encodes the momentum dependence of the
e
-ph interaction strength. We develop a Green’s-function method to model this structure, which naturally accounts for the phonon and interaction-strength dispersions, as well as the mixing of phonon momenta in the intermediate state. This model shows that the differences between the spectra can be fully explained by contrasting trends of the
e
-ph interaction through the Brillouin zone, being concentrated at the
Γ
and
K
points for the
π
∗
states while being significant at all momenta for the
σ
∗
states. Our results advance the interpretation of phonon excitations in RIXS and extend its applicability as a probe of
e
-ph interactions to a new range of out-of-equilibrium situations.
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Dec 2021
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I10-Beamline for Advanced Dichroism - scattering
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Yao
Guang
,
Yong
Peng
,
Zhengren
Yan
,
Yizhou
Liu
,
Junwei
Zhang
,
Xue
Zeng
,
Senfu
Zhang
,
Shilei
Zhang
,
David M.
Burn
,
Nicolas
Jaouen
,
Jinwu
Wei
,
Hongjun
Xu
,
Jiafeng
Feng
,
Chi
Fang
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Baoshan
Cui
,
Xixiang
Zhang
,
Guoqiang
Yu
,
Xiufeng
Han
Diamond Proposal Number(s):
[20183, 21868]
Abstract: The emergence of magnetic skyrmions, topological spin textures, has aroused tremendous interest in studying the rich physics related to their topology. While skyrmions promise high‐density and energy‐efficient magnetic memory devices for information technology, the manifestation of their nontrivial topology through single skyrmions and ordered and disordered skyrmion lattices could also give rise to many fascinating physical phenomena, such as chiral magnon and skyrmion glass states. Therefore, generating skyrmions at designated locations on a large scale, while controlling the skyrmion patterns, is the key to advancing topological magnetism. Here, a new, yet general, approach to the “printing” of skyrmions with zero‐field stability in arbitrary patterns on a massive scale in exchange‐biased magnetic multilayers is presented. By exploiting the fact that the antiferromagnetic order can be reconfigured by local thermal excitations, a focused electron beam with a graphic pattern generator to “print” skyrmions is used, which is referred to as skyrmion lithography. This work provides a route to design arbitrary skyrmion patterns, thereby establishing the foundation for further exploration of topological magnetism.
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Aug 2020
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[17612]
Open Access
Abstract: Magnetic skyrmions are two-dimensional magnetization swirls that stack in the form of tubes in the third dimension and which are proposed as prospective information carriers for nonvolatile memory devices due to their unique topological properties. From resonant elastic X-ray scattering measurements on Cu2OSeO3 with an in-plane magnetic field, we find that a state of perpendicularly ordered skyrmions forms, in stark contrast to the well-studied bulk state. The surface state is stable over a wide temperature range, unlike the bulk state in out-of-plane fields which is confined to a narrow region of the temperature-field phase diagram. In contrast to ordinary skyrmions found in the bulk, the surface state skyrmions result from the presence of magnetic interactions unique to the surface which stabilize them against external perturbations. The surface guiding makes the robust state particular interesting for racetracklike devices, ultimately allowing for much higher storage densities due to the smaller lateral footprint of the perpendicular skyrmions.
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Jan 2020
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Nicholas
Bukin
,
C.
Mckeever
,
Erick
Burgos-Parra
,
P. S.
Keatley
,
R. J.
Hicken
,
F. Y.
Ogrin
,
G.
Beutier
,
M.
Dupraz
,
H.
Popescu
,
N.
Jaouen
,
F.
Yakhou-Harris
,
Stuart
Cavill
,
G.
Van Der Laan
Open Access
Abstract: The magnetisation dynamics of the vortex core and Landau pattern of magnetic thin-film elements has been studied using holography with extended reference autocorrelation by linear differential operator (HERALDO). Here we present the first time-resolved x-ray measurements using this technique and investigate the structure and dynamics of the domain walls after excitation with nanosecond pulsed magnetic fields. It is shown that the average magnetisation of the domain walls has a perpendicular component that can change dynamically depending on the parameters of the pulsed excitation. In particular, we demonstrate the formation of wave bullet-like excitations, which are generated in the domain walls and can propagate inside them during the cyclic motion of the vortex core. Based on numerical simulations we also show that, besides the core, there are four singularities formed at the corners of the pattern. The polarisation of these singularities has a direct relation to the vortex core, and can be switched dynamically by the wave bullets excited with a magnetic pulse of specific parameters. The subsequent dynamics of the Landau pattern is dependent on the particular configuration of the polarisations of the core and the singularities.
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Oct 2016
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Erick Omar
Burgos Parra
,
Nicholas
Bukin
,
Maxime
Dupraz
,
Guillaume
Beutier
,
Sohrab
Redjai Sani
,
Horia
Popescu
,
Stuart
Cavill
,
Johan
Akerman
,
Nicolas
Jaouen
,
Paul
Keatley
,
Robert
Hicken
,
Gerrit
Van Der Laan
,
Feodor
Ogrin
Abstract: Time-averaged images of the magnetization within single layer spin transfer oscillators have been obtained using the holography with extended reference by autocorrelation linear differential operator (HERALDO) technique. Transport measurements on a Pd(5)-Cu(20)-Ni81Fe19(7)-Cu(2)-Pd(2) (in nm) stack with a 100 nm diameter nano-contact reveal the presence of vortex dynamics. Magnetic images of the device for injected current values of 24mA and -24mA suggest that a vortex has been ejected from the nano-contact and become pinned at the edge of the region that is visible through the Au mask.
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Feb 2016
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I06-Nanoscience (XPEEM)
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Marta
Elzo Aizarna
,
Reda
Moubah
,
Camille
Blouzon
,
Maurizio
Sacchi
,
Stéphane
Grenier
,
Rachid
Belkhou
,
Sarnjeet
Dhesi
,
Dorothée
Colson
,
Felipe
Torres
,
Miguel
Kiwi
,
Michel
Viret
,
Nicolas
Jaouen
Diamond Proposal Number(s):
[4840]
Abstract: Multiferroic materials are mostly antiferromagnets, often containing incommensurate magnetic arrangements stemming from the magnetoelectric interaction. Using soft x-ray resonant magnetic scattering, we show that these long-range structures induce a magnetization wriggle in cobalt layers deposited on top of BiFeO3 single crystals. This is understood using a simple interface exchange interactions model. It leads to the appearance of a magnetic anisotropy axis, which, in the particular BiFeO3/Co system, can be manipulated using an electric field. More generally, it is demonstrated here that through interfacial magnetic exchange, antiferromagnets can leave an imprint revealing some of their hidden properties, thus providing much richer effects than mere exchange bias.
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Jan 2015
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