I10-Beamline for Advanced Dichroism - scattering
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S.
Pylypenko
,
Moritz
Winter
,
U. K.
Rößler
,
D.
Pohl
,
R.
Kyrychenko
,
Marein
Rahn
,
B.
Achinuq
,
J. R.
Bollard
,
P.
Vir
,
G.
Van Der Laan
,
T.
Hesjedal
,
J.
Schultz
,
B.
Rellinghaus
,
C.
Felser
,
A.
Lubk
Diamond Proposal Number(s):
[28882]
Open Access
Abstract: Disordered two-dimensional (2D) lattices, including hexatic and various glassy states, are observed in a wide range of 2D systems including colloidal nanoparticle assemblies and fluxon lattices. Their disordered nature determines the stability and mobility of these systems, as well as their response to the external stimuli. Here we report on the controlled creation and characterization of a disordered 2D lattice of nontopological magnetic bubbles in the noncentrosymmetric ferrimagnetic alloy Mn1.4PtSn. By analyzing the type and frequency of fundamental lattice defects, such as dislocations, the orientational correlation, as well as the induced motion of the lattice in an external field, a nonergodic glassy state, stabilized by directional application of an external field, is revealed.
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Dec 2025
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[33454]
Open Access
Abstract: Magnetron sputtering offers a scalable route to magnetic topological insulators (MTIs) based on Cr-doped Sb2Te3. We combine a range of X-ray diffraction (XRD), reciprocal-space mapping (RSM), scanning transmission electron microscopy (STEM), scanning TEM-energy-dispersive X-ray spectroscopy (STEM-EDS), and X-ray absorption spectroscopy, and X-ray magnetic circular dichroism (XAS/XMCD) techniques to study the structure and magnetism of Cr-doped Sb2Te3 films. Symmetric 𝜃
-2𝜃
XRD and RSM establish a solubility window. Layered tetradymite order persists up to ∼10 at.-% Cr, while higher doping yields CrTe/Cr2Te3 secondary phases. STEM reveals nanocrystalline layered stacking at low Cr and loss of long-range layering at higher Cr concentrations, consistent with XRD/RSM. Magnetometry on a 6% film shows soft ferromagnetism at 5 K. XAS and XMCD at the Cr 𝐿2,3
edges exhibits a depth dependence: total electron yield (TE; surface sensitive) shows both nominal Cr2+ and Cr3+, whereas fluorescence yield (FY; bulk sensitive) shows a much higher Cr2+ weight. Sum rules applied to TEY give 𝑚𝐿=(0.20±0.04)
𝜇B
/Cr, and 𝑚𝑆=(1.6±0.2)
𝜇B
/Cr, whereby we note that the applied maximum field (3 T) likely underestimates 𝑚𝑆
. These results define a practical growth window and outline key parameters for MTI films.
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Oct 2025
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I10-Beamline for Advanced Dichroism - scattering
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Miming
Cai
,
Shangyuan
Wang
,
Yuelin
Zhang
,
Xiaoqing
Bao
,
Dekun
Shen
,
Jinghua
Ren
,
Lei
Qiu
,
Haiming
Yu
,
Zhenlin
Luo
,
Mathias
Kläui
,
Shilei
Zhang
,
Nicolas
Jaouen
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Ka
Shen
,
Jinxing
Zhang
Diamond Proposal Number(s):
[36632]
Abstract: Symmetry engineering is an effective approach for generating emergent phases and quantum phenomena. In magnetic systems, the Dzyaloshinskii-Moriya (DM) interaction is essential for stabilizing chiral spin textures. The symmetry manipulation of DM vectors, described in three dimensions, could provide a strategy toward creating abundant topologically magnetic phases. Here, we have achieved breaking the rotational and mirror symmetries of the three-dimensional DM vectors in a strongly correlated ferromagnet, which were directly measured through the nonreciprocal spin-wave propagations in both in-plane and out-of-plane magnetic field geometries. Combining cryogenic magnetic force microscopy and micromagnetic simulations, we discover a bimeron phase that emerges between the spin spiral and skyrmion phases under an applied magnetic field. Such an artificially manipulated DM interaction is shown to play a critical role in the formation and evolution of the large-area bimeron lattice, a phenomenon that could be realized across a broad range of materials. Our findings demonstrate that symmetry engineering of the DM vectors can be practically achieved through epitaxial strain, paving the way for the creation of diverse spin topologies and the exploration of their emergent functionalities.
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Sep 2025
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[36644]
Open Access
Abstract: The synthesis and magnetic properties of the intrinsic magnetic topological insulator MnBi2Te4, grown by magnetron sputtering, are investigated. While this growth method enables smoother morphologies than molecular beam epitaxy and is compatible with scalable processing, the metastable nature of MnBi2Te4 presents considerable challenges in phase control and magnetic uniformity. By systematically varying the relative sputter powers of Mn, Bi2Te3, and Te targets, conditions that favor the formation of near-stoichiometric MnBi2Te4, as supported by X-ray diffraction, atomic force microscopy, and energy-dispersive X-ray spectroscopy, are identified. These films exhibit reduce surface roughness and lower twin-domain density compared to Mn-rich counterparts, which show evidence of phase separation and structural disorder. Magnetometry and X-ray magnetic circular dichroism reveal that both film types exhibit sizable Mn moments, although signatures of antiferromagnetic order are only weakly expressed and appear sensitive to composition and morphology. Despite producing structurally well-ordered films, clear linear dichroism attributable to A-type antiferromagnetic ordering is not observed, suggesting magnetic inhomogeneity or suppression of interlayer coupling. These results highlight the compositional sensitivity of sputtered MnBi2Te4 and underline the difficulties in stabilizing the intrinsic magnetic topological phase in thin-film form.
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Aug 2025
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Abstract: Resonant inelastic x-ray scattering (RIXS) is a powerful tool for probing the ground-state electronic configurations of actinide materials. However, in certain metallic uranium compounds, RIXS fails to detect excitations from the ground-state multiplet. This absence is attributed to strong hybridization between uranium 5𝑓 electrons and conduction electrons. In the present study, we extend RIXS investigations to a 16µg sample of the metallic compound AmFe2, marking an experiment at the 𝑀4,5 edges of a transuranium material. Americium in AmFe2 adopts a trivalent (Am3+) state with a 5𝑓6 electronic configuration having a 𝐽 = 0 ground state, with the 5𝑓 states located approximately 3 eV below 𝐸𝐹. The RIXS spectra exhibit well-resolved features that are in good agreement with theory. The localized nature of the 5𝑓 electrons in AmFe2 permits the observation of multiplet excitations despite its metallic character. These observations extend our understanding of RIXS in actinide systems.
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Aug 2025
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I10-Beamline for Advanced Dichroism - scattering
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Bernd
Rellinghaus
,
Andy
Thomas
,
Moritz
Winter
,
Marein C.
Rahn
,
Alexandr S.
Sukuhanov
,
Alexander
Than
,
Sebastian
Schneider
,
Alessandro
Pignedoli
,
Maria
Azhar
,
Karin
Everschor-Sitte
,
Jochen
Geck
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Praveen
Vir
,
Claudia
Felser
,
Darius
Pohl
Diamond Proposal Number(s):
[28882]
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Jul 2025
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Ethan L.
Arnold
,
Emily
Heppell
,
Rabindra
Basnet
,
Binshuo
Zhang
,
Jieyi
Liu
,
Javier
Herrero-Martin
,
Charles
Guillemard
,
Yanfeng
Guo
,
Jin
Hu
,
Dirk
Backes
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
Open Access
Abstract: This study investigates the intrinsic magnetism and field-driven spin alignment in NiI2 using X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD). NiI2, a van der Waals material, exhibits helimagnetic and type-II multiferroic behavior. This study reveals robust XMCD signals across paramagnetic, antiferromagnetic, and helimagnetic phases under applied out-of-plane fields up to 6 T, while no net moment emerges at zero field. Atomic multiplet calculations confirm a covalent Ni 3d ground state with a significantly reduced spin moment. The results establish the intrinsic nature of NiI2's magnetism and clarify its field-driven spin alignment mechanism. This comprehensive spectroscopic characterization lays the foundation for future applications of NiI2 in advanced spintronic and multiferroic devices, despite challenges posed by its low transition temperature in the monolayer limit. Future research should focus on enhancing its critical temperature through doping, strain engineering, or heterostructure fabrication.
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Jun 2025
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C. A. F.
Vaz
,
G.
Van Der Laan
,
S. A.
Cavill
,
H. A.
Dürr
,
A.
Fraile Rodríguez
,
F.
Kronast
,
W.
Kuch
,
P.
Sainctavit
,
G.
Schütz
,
E.
Weschke
,
F.
Wilhelm
,
H.
Wende
Abstract: X-ray magnetic circular dichroism (XMCD) is the difference in X-ray absorption between left and right circularly polarized light in magnetic materials. It is the X-ray counterpart of the magneto-optic effect for visible light but shows a magnetic contrast up to three orders of magnitude higher. The exploration of XMCD using high-flux, monochromatic and polarization-variable synchrotron sources has advanced the understanding of magnetism and magnetic materials, in particular, when combined with spectral analysis based on powerful sum rules that enable the quantification of spin and orbital moments with elemental, even chemical, selectivity and high sensitivity. As an essential cornerstone of techniques to probe magnetic nanostructures and spin textures as well as their dynamics, XMCD has become an indispensable tool for the study of magnetism at the nanoscale and atomic scale. This Primer provides an overview of the principles and physics underlying XMCD, the experimental techniques used to measure it and its application to the study and understanding of fundamental and technologically relevant magnetic phenomena.
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May 2025
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I09-Surface and Interface Structural Analysis
I10-Beamline for Advanced Dichroism - scattering
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Naina
Kushwaha
,
Olivia
Armitage
,
Brendan
Edwards
,
Liam
Trzaska
,
Jennifer
Rigden
,
Peter
Bencok
,
Deepnarayan
Biswas
,
Tien-Lin
Lee
,
Charlotte
Sanders
,
Gerrit
Van Der Laan
,
Peter
Wahl
,
Phil D. C.
King
,
Akhil
Rajan
Diamond Proposal Number(s):
[33239, 38049]
Open Access
Abstract: Chromium ditelluride, CrTe2, is an attractive candidate van der Waals material for hosting 2D magnetism. However, how the room-temperature ferromagnetism of the bulk evolves as the sample is thinned to the single-layer limit has proved controversial. This, in part, reflects its metastable nature, vs. a series of more stable self-intercalation compounds with higher relative Cr:Te stoichiometry. Here, exploiting a recently developed method for enhancing nucleation in molecular-beam epitaxy growth of transition-metal chalcogenides, we demonstrate the selective stabilisation of high-coverage CrTe2 and Cr2+εTe3 epitaxial monolayers. Combining X-ray magnetic circular dichroism, scanning tunnelling microscopy, and temperature-dependent angle-resolved photoemission, we demonstrate that both compounds order magnetically with a similar TC. We find, however, that monolayer CrTe2 forms as an antiferromagnetic metal, while monolayer Cr2+εTe3 hosts an intrinsic ferromagnetic semiconducting state. This work thus demonstrates that control over the self-intercalation of metastable Cr-based chalcogenides provides a powerful route for tuning both their metallicity and magnetic structure, establishing the CrxTey system as a flexible materials class for future 2D spintronics.
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May 2025
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Peng
Chen
,
Jieyi
Liu
,
Yifan
Zhang
,
Puyang
Huang
,
Jack
Bollard
,
Yiheng
Yang
,
Ethan L.
Arnold
,
Xinqi
Liu
,
Qi
Yao
,
Fadi
Choueikani
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Xufeng
Kou
Abstract: MnBi2Te4-based superlattices not only enrich the materials family of magnetic topological insulators, but also offer a platform for tailoring magnetic properties and interlayer magnetic coupling through the strategic insertion layer design. Here, we present the electrical and magnetic characterization of (Bi1−xSbx)2Te3-intercalated MnBi2Te4 multilayers grown by molecular beam epitaxy. By precisely adjusting the Sb-to-Bi ratio in the spacer layer, the magneto-transport response is modulated, unveiling the critical role of Fermi level tuning in optimizing the anomalous Hall signal and reconfiguring the magnetic ground state. Moreover, by varying the interlayer thickness, tunable magnetic coupling is achieved, enabling precise control over ferromagnetic and antiferromagnetic components. These findings pave the way for the exploration of versatile magnetic topological phases in quantum materials systems.
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Feb 2025
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