I09-Surface and Interface Structural Analysis
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Leyi
Loh
,
Han
Yan
,
Lixin
Liu
,
Yuan
Chen
,
Esther Lilian
Gray
,
Kamal Kumar
Paul
,
Deepnarayan
Biswas
,
Tien-Lin
Lee
,
Takashi
Taniguchi
,
Kenji
Watanabe
,
Mauro
Brotons-Gisbert
,
Yan
Wang
,
Manish
Chhowalla
Diamond Proposal Number(s):
[38012, 39914, 38086]
Open Access
Abstract: Unintentional doping from dielectrics can impact the electronic properties of two-dimensional transition metal dichalcogenide (2D TMD) semiconductors. Our recent work shows that high-dielectric-constant (k) ZrO2 is an electrostatically inert dielectric for 2D MoS2, supported by X-ray spectroscopy (XPS) and electrical measurements. Here, we expand this work through gate-controlled photoluminescence (PL) of monolayer MoS2 placed on different substrates. MoS2 on ZrO2 exhibits a low carrier concentration, indicated by a small trion-to-exciton ratio (X–/X0) of 0.5, similar to those on high-quality hBN. At a high electrostatic doping of ∼1013 cm–2, MoS2 on high-k ZrO2 reveals a slight exponential dependence of X–/X0 versus carrier concentration, while MoS2 on SiO2 shows strong exponential characteristics even at low gating (1012 cm–2) due to substantial electron doping from substrate-induced disorder tail states. Our findings provide insights into the doping mechanisms in industry-compatible amorphous dielectrics and evaluate their potential for scalable optoelectronic devices.
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Aug 2026
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I05-ARPES
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Chakradhar
Sahoo
,
Suman Kumar
Chakraborty
,
Anbalagan
Kousika
,
Alfred J. H.
Jones
,
Manas
Sharma
,
Thomas S.
Nielsen
,
Zhihao
Jiang
,
Ihsan A.
Kolasseri
,
Subhadip
Das
,
Matthew D.
Watson
,
Cephise
Cacho
,
Kenji
Watanabe
,
Takashi
Taniguchi
,
Yong P.
Chen
,
Tony F.
Heinz
,
Ananth
Govind Rajan
,
Prasana K.
Sahoo
,
Søren
Ulstrup
Diamond Proposal Number(s):
[36290, 38414]
Abstract: Atomic-scale control over band alignment in single-layer lateral heterostructures (LHSs) of dissimilar transition metal dichalcogenides (TMDCs) is critical for next-generation electronic, optoelectronic, and quantum technologies. However, direct experimental access to interfacial electronic states with nanometer precision remains a significant challenge. Here, we employ angle-resolved photoemission spectroscopy with nanoscale spatial resolution (nanoARPES) to directly map the epitaxial alignment and valence band evolution across the MoSe2–WSe2 LHSs. By combining nanoARPES with spatially resolved photoluminescence, we correlate the evolution of the valence band maximum and exciton features across both atomically sharp and compositionally graded diffusive interfaces. We identified type-II band alignments governed by both material composition and interstitial-induced modifications of band offsets in close agreement with density functional theory calculations. These results reveal fundamental mechanisms of electronic structure modulation at 1D TMDC heterointerfaces and provide a robust platform for tailored band engineering in van der Waals materials.
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Apr 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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Diamond Proposal Number(s):
[36056]
Open Access
Abstract: Photocatalytic micro/nanomotors have emerged as promising tools for environmental remediation, biosensing, and targeted delivery. To enhance their light-driven propulsion, significant efforts have focused on engineering semiconductor heterostructures, which promote charge separation. However, a clear understanding of how these architectures govern photocatalytic mechanisms and influence motion performance remains limited. Here, we design a visible light-responsive nanomotor based on a Fe2O3-Pt-TiO2 trilayered heterostructure, combining narrow-bandgap α-Fe2O3 and wide-bandgap TiO2 with an intermediate Pt layer. Remarkably, Fe2O3-TiO2 nanomotors without the Pt layer exhibit only modest propulsion under visible light, whereas the inclusion of Pt significantly enhances their motility. Through advanced techniques, including in situ synchrotron radiation-based near-ambient pressure X-ray photoelectron spectroscopy and transient absorption spectroscopy, we reveal that Pt serves as an efficient electron mediator, enabling directional charge transfer across the heterojunction. This study provides fundamental insights into charge transport in multicomponent nanomotors and introduces a rational strategy for designing efficient photoactive systems.
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Jun 2025
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I16-Materials and Magnetism
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Ludmila
Leroy
,
Shih-Wen
Huang
,
Chun-Chien
Chiu
,
Sheng-Zhu
Ho
,
Janine
Dössegger
,
Cinthia
Piamonteze
,
Yi-Chun
Chen
,
Elsa
Abreu
,
Alessandro
Bombardi
,
Jan-Chi
Yang
,
Urs
Staub
Open Access
Abstract: Thin films’ properties can be greatly influenced by their supporting growth substrates. Even in the so-called strain-free heterostructure films, it is still unclear whether there will be no interfacial electronic reconstructions induced by the underlying substrates. Here, we report the studies of SrTiO3 (STO) films in the freestanding form (FS) with a thickness ranging from 20 to 80 nm. These STO films, by default, are in a strain-free state; they exhibit distinct properties not seen in both bulk and strain-free heterostructure forms. Our films show an enhanced antiferrodistortive (AFD) phase transition temperature with a preferential in-plane rotation axis for the TiO6 octahedra. The anisotropic Ti orbital occupancy around the surface signals the departure of its properties from the bulk. Moreover, we have found that the in-plane ferroelectricity can be strengthened by the reduced dimensionality, establishing that the dimensionality control is an important factor for enhancing STO’s ferroelectric response.
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May 2025
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Zhengang
Dong
,
Marios
Hadjimichael
,
Bernat
Mundet
,
Jaewon
Choi
,
Charles C.
Tam
,
Mirian
Garcia-Fernandez
,
Stefano
Agrestini
,
Claribel
Domínguez
,
Regan
Bhatta
,
Yue
Yu
,
Yufeng
Liang
,
Zhenping
Wu
,
Jean-Marc
Triscone
,
Chunjing
Jia
,
Ke-Jin
Zhou
,
Danfeng
Li
Diamond Proposal Number(s):
[32305]
Open Access
Abstract: Superconductivity in infinite-layer nickelates has stirred much research interest, to which questions regarding the nature of superconductivity remain elusive. A critical leap forward to address these intricate questions is through the growth of high-crystallinity infinite-layer nickelates, including the “parent” phase. Here, we report the synthesis of a high-quality thin-film nickelate, NdNiO2. This is achieved through the growth of a perovskite precursor phase (NdNiO3) of superior crystallinity on the NdGaO3 substrate by off-axis RF magnetron sputtering and a low-temperature topochemical reduction using NaH. We observe a nonlinear Hall effect at low temperatures in this “non-doped” phase. We further study the electronic properties using advanced X-ray scattering and first-principles calculations. We observe spectroscopic indications of the enhanced two-dimensionality and a reduced hybridization of Nd 5d and Ni 3d orbitals. These findings unlock new pathways for preparing high-quality infinite-layer nickelates and provide new insights into the intrinsic features of these compounds.
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Jan 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[30748]
Open Access
Abstract: The poor soft tissue contrast of X-ray CT necessitates contrast agent use to improve diagnosis across disease applications, yet their poor detection sensitivity requires high injected doses, which restrict use in at-risk populations. Dark-field X-ray imaging is emerging as a more sensitive alternative to traditional attenuation-based imaging, leveraging scattered radiation to produce contrast. Yet aside from large, short-lived microbubbles, the alternate physics of dark-field detection has yet to be exploited for contrast agent development. Here we demonstrate that high-Z nanoparticles can provide a new means to producing dark-field image contrast, promoting scatter via a higher rather than lower electron density compared to microbubbles, increasing detection sensitivity compared to attenuation-based detection of a clinical iodine-based agent at an equivalent X-ray dose. As the use of dark-field X-ray imaging expands into more common clinical usage, this will support the development of a new class of nanoparticulate contrast agents.
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Nov 2024
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[32087, 32301]
Open Access
Abstract: Magnetic skyrmions are topologically protected spin textures with emergent particle-like behaviors. Their dynamics under external stimuli is of great interest and importance for topological physics and spintronics applications alike. So far, skyrmions are only found to move linearly in response to a linear drive, following the conventional model treating them as isolated quasiparticles. Here, by performing time and spatially resolved resonant elastic X-ray scattering of the insulating chiral magnet Cu2OSeO3, we show that for finite-sized skyrmion crystallites, a purely linear temperature gradient not only propels the skyrmions but also induces continuous rotational motion through a chiral lattice torque. Consequently, a skyrmion crystallite undergoes a rolling motion under a small gradient, while both the rolling speed and the rotational sense can be controlled. Our findings offer a new degree of freedom for manipulating these quasiparticles toward device applications and underscore the fundamental phase difference between the condensed skyrmion lattice and isolated skyrmions.
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Sep 2024
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Yong
Wang
,
Wanting
He
,
Ruiqi
Yang
,
Darius
Pohl
,
Bernd
Rellinghaus
,
Peter A. C.
Neathway
,
Zahra
Kalantari Bolaghi
,
Chen
Wang
,
Ting
Yu
,
Fan
Yang
,
Guozhu
Chen
,
Mohamed
Chaker
,
Aycan
Yurtsever
,
Gianluigi A.
Botton
,
Yannan
Liu
,
Dongling
Ma
Abstract: Plasmonic nanomaterials such as Au, Ag, and Cu are widely recognized for their strong light–matter interactions, making them promising photothermal materials for solar steam generation. However, their practical use in water evaporation is significantly limited by the trade-off between high costs and poor stability. In this regard, we introduce a novel, nonmetallic dual plasmonic TiN/MoO3–x composite. This composite features a three-dimensional, urchin-like biomimetic structure, with plasmonic TiN nanoparticles embedded within a network of plasmonic MoO3–x nanorods. As a solar absorber, the TiN/MoO3–x composite achieves a high evaporation rate of ∼2.05 kg m–2 h–1 with an energy efficiency up to 106.7% under 1 sun illumination, outperforming the state-of-the-art plasmonic systems. The high photothermal stability and unique dual plasmonic nanostructure of the TiN/MoO3–x composite are demonstrated by advanced in situ laser-heating transmission electron microscopy and photon-induced near-field electron microscopy/electron energy-loss spectroscopy, respectively. This work provides new inspiration for the design of plasmonic materials.
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Aug 2024
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[30616, 31619]
Open Access
Abstract: Spintronic devices incorporating magnetic skyrmions have attracted significant interest recently. Such devices traditionally focus on controlling magnetic textures in 2D thin films. However, enhanced performance of spintronic properties through the exploitation of higher dimensionalities motivates the investigation of variable-thickness skyrmion devices. We report the demonstration of a skyrmion injection mechanism that utilizes charge currents to drive skyrmions across a thickness step and, consequently, a metastability barrier. Our measurements show that under certain temperature and field conditions skyrmions can be reversibly injected from a thin region of an FeGe lamella, where they exist as an equilibrium state, into a thicker region, where they can only persist as a metastable state. This injection is achieved with a current density of 3 × 108 A m–2, nearly 3 orders of magnitude lower than required to move magnetic domain walls. This highlights the possibility to use such an element as a skyrmion source/drain within future spintronic devices.
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May 2024
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I10-Beamline for Advanced Dichroism - scattering
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Bin
He
,
Haonan
Jin
,
Dongfeng
Zheng
,
Yizhou
Liu
,
Jialiang
Li
,
Yue
Hu
,
Yuqiang
Wang
,
Junwei
Zhang
,
Yong
Peng
,
Caihua
Wan
,
Tao
Zhu
,
Xiufeng
Han
,
Shilei
Zhang
,
Guoqiang
Yu
Diamond Proposal Number(s):
[27692]
Abstract: Antiferromagnetic (AFM) skyrmions are magnetic vortices composed of antiparallell-aligned neighboring spins. In stark contrast to conventional skyrmions based on ferromagnetic order, AFM skyrmions have vanished stray fields, higher response frequencies, and rectified translational motion driven by an external force. Therefore, AFM skyrmions promise highly efficient spintronics devices with high bit mobility and density. Nevertheless, the experimental realization of intrinsic AFM skyrmions remains elusive. Here, we show that AFM skyrmions can be nucleated via interfacial exchange coupling at the surface of a room-temperature AFM material, IrMn, exploiting the particular response from uncompensated moments to the thermal annealing and imprinting effects. Further systematic magnetic characterizations validate the existence of such an AFM order at the IrMn/CoFeB interfaces. Such AFM skyrmions have a typical size of 100 nm, which presents pronounced robustness against field and temperature. Our work opens new pathways for magnetic topological devices based on AFM skyrmions.
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Feb 2024
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