I16-Materials and Magnetism
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Diamond Proposal Number(s):
[39446]
Abstract: We characterize the magnetic ground state of the newly synthesized lanthanide intermetallic GdNiSn4via resonant elastic x-ray scattering measurements. This compound forms distorted square nets of Gd that initially order magnetically below 23 K, followed by a lower-temperature transition at 16 K. Our scattering data identify the ground state order as a single-q incommensurate, collinear order that slides towards a commensurate wave vector above the 16 K transition. Magnetic symmetry analysis combined with azimuthal dependence resolves the ground state magnetic structure as a moment-modulated spin density wave state with Gd moments oriented parallel to the in-plane 𝑎-axis. We discuss connections between the observed magnetic order and electronic properties in this square-net compound.
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Jul 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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Ellen M.
Kiens
,
Nicolas
Gauquelin
,
Arno
Annys
,
Emma
Van Der Minne
,
Iris C. G.
Van Den Bosch
,
Matthijs A.
Van Spronsen
,
Zezhong
Zhang
,
Annick
De Backer
,
Sandra
Van Aert
,
Jo
Verbeeck
,
Gertjan
Koster
,
Bastian
Mei
,
Frank M. F.
De Groot
,
Christoph
Baeumer
Diamond Proposal Number(s):
[33107, 31118]
Abstract: Transition metal oxides exhibit a wide range of tunable electronic properties arising from the complex interplay of charge, spin, and lattice degrees of freedom, governed by their 𝑑 orbital configurations, making them particularly interesting for oxide electronics and (electro)catalysis. Perovskite oxide heterointerfaces offer a promising route to engineer these orbital states. In this work, we tune the Co3𝑑 orbital occupancy in LaCoO3 from a partial 𝑑7 to a partial 𝑑5 state through interfacial engineering with LaTiO3, LaMnO3, LaAlO3, and LaNiO3. Using x-ray absorption spectroscopy combined with charge transfer multiplet calculations, we identify differences in the Co valence and spin state for the series of oxide heterostructures. LaTiO3 and LaMnO3 interfaces result in interfacial charge transfer towards LaCoO3, resulting in a partial 𝑑7 orbital occupancy, while a LaNiO3 interface results in a partial Co 𝑑5 occupancy. Strikingly, a LaAlO3 spacer layer between LaNiO3 and LaCoO3 results in a Co 𝑑6 low-spin state. These results indicate that the Co spin state, like the valence state, is governed by the interfacial environment. High-resolution scanning transmission electron microscopy imaging reveals a clear connection between strain and spin configuration, emphasizing the importance of structural control at oxide interfaces. Overall, this work demonstrates that interfacial engineering simultaneously governs orbital occupancy and spin state in correlated oxides, advancing spin-engineering strategies in correlated oxides and offering new insights for the rational design of functional oxide heterostructures.
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Jun 2026
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I06-Nanoscience (XPEEM)
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Benjamin A.
Brereton
,
Soumyarup
Hait
,
Ahmet
Yagmur
,
Christy
Kinane
,
Francesco
Maccherozzi
,
Michele
Conroy
,
Satoshi
Sasaki
,
Thomas A.
Moore
,
Sarnjeet S.
Dhesi
,
Sean
Langridge
,
Christopher H.
Marrows
Diamond Proposal Number(s):
[37770, 38770]
Open Access
Abstract: Topological insulators and skyrmion-hosting, chiral magnetic multilayers are two well-explored areas of modern condensed matter physics, each offering unique advantages for spintronics applications. In this paper, we demonstrate the optimization process for the growth of a Bi2Se3/buffer/[Pt/CoB/Ru]×𝑁 heterostructure that combines these two material classes: the Bi2Se3 epilayer was grown by molecular beam epitaxy before transfer under ultrahigh vacuum to a separate growth chamber where the polycrystalline metallic multilayer was sputter deposited. The structure of the samples was characterized by cofitted x-ray and polarized neutron reflectometry measurements and scanning transmission electron microscopy. Polarized neutron models and standard magnetometry show that a buffer layer exceeding a critical thickness is required to obtain the desired uniform, perpendicular magnetic anisotropy in every magnetic layer in the multilayer. Samples with both Ta and Mo buffers were used requiring thicknesses of 1.5 and 0.9 nm, respectively. In minimizing the Bi2Se3 terracing, buffered samples yield well-defined, out-of-plane, magnetic domains suitable for spin-orbit torque-induced manipulation as determined by x-ray photoemission electron microscopy.
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Jun 2026
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I06-Nanoscience (XPEEM)
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Diamond Proposal Number(s):
[6230, 1771]
Open Access
Abstract: Epitaxial films of the ferromagnetic manganite La0.7Sr0.3MnO3 on substrates of the ferroelectric perovskite BaTiO3 are known to display sharp magnetic changes and large magnetoelectric effects when the film is strained by the substrate undergoing thermally driven structural transitions and ferroelectric domain switching, respectively. However, only a single component of the in-plane magnetization has been hitherto imaged. Here we present magnetic vector maps—obtained from photoemission electron microscopy images with magnetic contrast from x-ray magnetic circular dichroism—to show that the electrically and thermally driven changes of local and global magnetization are deterministically influenced by the state of the substrate while also being complex and sample dependent. Our findings, supported by ferromagnetic resonance data and vibrating sample magnetometry, reveal that the behavior of La0.7Sr0.3MnO3 films on BaTiO3 substrates is not well predicted from knowledge of each system, probably due to long-range strain between BaTiO3 domains. In the future, it would be interesting to reduce complexity by patterning the film into regions between which magnetic communication is negligible.
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May 2026
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I19-Small Molecule Single Crystal Diffraction
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S. D.
Nabi
,
L.
Facheris
,
V.
Romerio
,
V.
Kocsis
,
K. Yu.
Povarov
,
D.
Sheptyakov
,
J.
Lass
,
D. G.
Mazzone
,
H.
Kikuchi
,
T.
Masuda
,
S. A.
Barnett
,
D. R.
Allan
,
Z.
Yan
,
S.
Gvasaliya
,
A.
Zheludev
Diamond Proposal Number(s):
[37825]
Abstract: We report comprehensive thermodynamic and neutron scattering measurements on the 𝑆=3/2 antiferromagnet Cs2CoI4, a member of the thoroughly studied family of frustrated magnets Cs2𝑀𝑋4 (𝑀=Cu, Co, Ru, 𝑋=Br, Cl, I, O). Unlike previously studied members, Cs2CoI4 undergoes a structural phase transition, for which we determine the low-temperature crystallographic structure. The resulting symmetry reduction strongly affects both the magnetic exchange interactions and single-ion anisotropy. Despite the large parameter space, we propose a minimal magnetic Hamiltonian that reasonably captures the observed excitation spectrum, analyzed using extended SU(4) linear spin-wave theory.
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May 2026
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I05-ARPES
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Z. W.
Riedel
,
P. A. E.
Murgatroyd
,
C. S.
Kengle
,
P. M. T.
Trocado Vianez
,
A.
Schmidt
,
X.
Du
,
K.
Allen
,
Ti. K.
Kim
,
C.
Lane
,
Y. W.
Li
,
J.-X.
Zhu
,
J. D.
Thompson
,
F.
Ronning
,
S. M.
Thomas
,
P. F. S.
Rosa
,
E. D.
Bauer
Diamond Proposal Number(s):
[41855]
Abstract: The chemical flexibility of the 𝑅𝑀6𝑋6 stoichiometry, where an 𝑓-block element is intercalated in the CoSn structure type, allows for the tuning of flatbands associated with kagome lattices to the Fermi level and for emergent phenomena due to interactions between the 𝑓- and 𝑑-electron lattices. Yet, 5𝑓 members of the “166” compounds are underrepresented compared with 4𝑓 members. Here, we report single-crystal growth of UCr6Ge6, which crystallizes in a monoclinically distorted Y0.5Co3Ge3-type structure. The real-space character of the modulation, which is unique within the 𝑅𝑀6𝑋6 family, is approximated by a 3×1×2 supercell of the average monoclinic cell. The compound has kagome-lattice flatbands near the Fermi level and a moderately enhanced electronic heat capacity, as evidenced by its low-temperature Sommerfeld coefficient (𝛾=86.5 mJ mol−1 K−2) paired with band structure calculations. The small, isotropic magnetization and featureless resistivity of UCr6Ge6 suggest itinerant uranium 5𝑓 electrons and Pauli paramagnetism. Angle-resolved photoemission spectroscopy results provide evidence for uranium 5𝑓 weight at the Fermi level and for a flatband near the Fermi level associated with the chromium 3𝑑 kagome lattice. The isotropic magnetic behavior of the uranium 5𝑓 electrons starkly contrasts with localized behavior in other uranium 166 compounds, highlighting the high tunability of the magnetic ground state across the material family.
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May 2026
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[40166]
Abstract: We report bulk magnetic properties of the monoclinic lanthanide tantalates, 𝑀′−𝐿𝑛TaO4 (𝐿𝑛= Tb, Dy, Ho, Er), where the magnetic 𝐿𝑛3+ ions are arranged on a distorted 2D square lattice. The heavier analog 𝑀′−YbTaO4 has been investigated as a spin-orbit-coupled, quasi-two-dimensional frustrated magnet, and the properties of the other 𝑀′−𝐿𝑛TaO4 are expected to vary depending on the electronic configuration of the 𝐿𝑛 ion, namely, Kramers vs non-Kramers behavior and different crystal electric field parameters. In this work, powder neutron diffraction is used to confirm the crystal structure for 𝐿𝑛= Tb, Ho, Er, and to determine the magnetic structure of 𝑀′−TbTaO4, which displays long-range antiferromagnetic (AFM) order below 𝑇N=2.1K. The Tb3+ moments are aligned primarily along the 𝑐 axis with AFM nearest-neighbor interactions. Susceptibility data suggest that 𝑀′−DyTaO4 may display short-range ordering around 2.7 K, while 𝑀′−HoTaO4 and 𝑀′−ErTaO4 show AFM correlations but do not order above 1.8 K. Measurements of the magnetic specific heat provide evidence for a Kramers doublet ground state in 𝑀′−ErTaO4, similar to its heavier analog 𝑀′−YbTaO.
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Apr 2026
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I06-Nanoscience (XPEEM)
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Purnima P.
Balakrishnan
,
Hemian
Yi
,
Zi-Jie
Yan
,
Wei
Yuan
,
Andreas
Suter
,
Christopher J.
Jensen
,
Pascal
Manuel
,
Fabio
Orlandi
,
Takayasu
Hanashima
,
Christy J.
Kinane
,
Andrew J.
Caruana
,
Dirk
Backes
,
Padraic
Shafer
,
Brian B.
Maranville
,
Zaher
Salman
,
Thomas
Prokscha
,
Cui-Zu
Chang
,
Alexander J.
Grutter
Diamond Proposal Number(s):
[42224]
Abstract: The search for chiral topological superconductivity in magnetic topological insulator (TI)-FeTe heterostructures is a key frontier in condensed matter physics, with potential applications in topological quantum computing. The combination of ferromagnetism, superconductivity, and topologically nontrivial surface states brings together the key elements required for chiral Majorana physics. In this work, we examine the interplay between magnetism and superconductivity at the interfaces between FeTe and a series of Te-based TI overlayers. In both Te/FeTe and superconducting MnBi2Te4/FeTe, any interfacial suppression of antiferromagnetism must affect at most a few nanometers. On the other hand, (Bi,Sb)2Te3/FeTe layers exhibit near-total suppression of antiferromagnetic ordering. Ferromagnetic Cr𝑥(Bi,Sb)2−𝑥Te3 (CBST)/FeTe bilayers exhibit net magnetization in both CBST and FeTe layers, with evidence of interactions between superconductivity and ferromagnetism. These observations identify magnetic TI/FeTe interfaces as an exceptionally robust platform to realize chiral topological superconductivity.
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Oct 2025
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I06-Nanoscience (XPEEM)
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M.
Boldrin
,
A.
Bagri
,
D.
Barlettani
,
E.
Teather
,
L.
Squillantini
,
M.
De Souza
,
R. B.
Pontes
,
A. G.
Silva
,
T. J. A.
Mori
,
R.
Perry
,
R.
Lora-Serrano
,
E.
Granado
,
E. M.
Bittar
,
L. S. I.
Veiga
,
L.
Bufaiçal
Diamond Proposal Number(s):
[35100]
Abstract: The La2CoMnO6 (LCMO) perovskite has received a lot of attention due to its near-room-temperature magnetodielectric effect. Despite the recent efforts, the mechanism ruling the correlation between its magnetic and dielectric properties is not yet fully understood. In order to address this issue, we conducted a detailed investigation of the coupling between the structural, electronic, and magnetic properties of a polycrystalline LCMO sample. Using magnetic field-dependent x-ray powder diffraction and measurements with a capacitive dilatometer, we show that applying an external magnetic field decreases the unit cell volume, thereby modifying the octahedral distortions. Experiments involving temperature and field-dependent x-ray absorption spectroscopy at the Co-𝐿2,3 edges provide further evidence that the spin-orbit interaction of outermost Co 3𝑑 orbital and the field-induced enhancement of covalence effects are the key contributors to the magnetostrictive effects. From a detailed analysis using multiplet and density functional theory calculations, we propose that the field-induced modulations of the orbital hybridization and the ligand-to-metal charge transfer are responsible for the changes in the dielectric response of LCMO, thus enabling a direct coupling between magnetic, elastic, and dielectric properties in this material.
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Sep 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[16952]
Open Access
Abstract: Atomic resolution imaging is key to understanding thin film growth and how a particular set of conditions influences properties. Whilst such imaging in the scanning transmission electron microscope (STEM) has had a transformative impact in nanoscience, it forms projection images and provides no direct information about displacements perpendicular to the image plane. In this article, we show that it is possible to make atomic resolution maps of the direction and magnitude of La displacements at ∼30∘ to the imaging plane in a La2CoMnO6 thin film on (111) LSAT (LaAlO3−La(Sr,Ta)O3) using a four-dimensional STEM (4DSTEM) methodology. This reveals that the La modulation lies preferentially in the interface plane, and is strongly suppressed close to the epitaxial interface, and further reveals how the modulation varies with distance from the interface with unit cell resolution. These details would be completely invisible to all prior techniques in electron microscopy and this sheds light on why this particular substrate in this orientation best promotes double perovskite cation ordering, and the consequent optimal magnetic ordering for this thin film system. The approach used herein of fitting atomic resolution 4DSTEM data to determine crystal parameters opens the door for a new era of atomic-resolution crystallography.
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Sep 2025
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