E02-JEM ARM 300CF
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Xinjuan
Li
,
Zhao
Jiang
,
Si
Chen
,
Yi
Tang
,
Bofeng
Xue
,
Tianhao
Wu
,
Yang
Lu
,
Xavier
Moya
,
Akshay
Rao
,
Zhongzheng
Yu
,
Caterina
Ducati
Diamond Proposal Number(s):
[39081]
Open Access
Abstract: Perovskite quantum dots (PeQDs) offer high photoluminescence quantum efficiencies, precise spectral tunability, and solution-processability, making them promising for advanced optoelectronics. However, their structural and defect evolution under thermal stress remains poorly understood. Here, direct nanoscale insights are provided into temperature-driven phase transition and defect dynamics in CsPbBr3 PeQDs using high-resolution, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, 4D STEM, and photoluminescence spectroscopy. Sub-ångström imaging at room temperature reveals inherent atomic features and octahedral tilting of the lead halide perovskite lattice in PeQDs, suggesting a pre-tilted, low-symmetry state before thermal perturbation. The cryogenic cooling induces a reversible orthorhombic-to-monoclinic phase transition, distinct from bulk perovskite behavior and accompanied by severe strain localization exceeding 20% at surfaces and grain boundaries. A controlled cryogenic post-synthesis treatment can effectively heal defects and improve radiative recombination, whereas prolonged cryo-treatment introduces irreversible structural degradation. These findings highlight the intrinsic structural flexibility of PeQDs and provide a scalable post-synthesis treatment method to optimize the stability and efficiency of QDs for various optoelectronic applications.
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Dec 2025
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I06-Nanoscience (XPEEM)
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Lingzhi
Wen
,
Cong
Li
,
Guanshihan
Du
,
Sijie
Wu
,
Jianbing
Zhang
,
Xiaoyin
Pan
,
Clodomiro
Cafolla
,
Lizhe
Hu
,
Yongjun
Wu
,
Zijian
Hong
,
Qing
He
,
Pu
Yu
Diamond Proposal Number(s):
[42042, 36503, 34602, 26142, 22361, 38419]
Abstract: Topological polar textures have garnered significant attention for next-generation electronic devices due to associated emergent functionalities (e.g., chirality, enhanced conductivity, and negative capacitance). Most studies stabilize topological textures using depolarization field in ferroelectric- dielectric superlattices or heterostructures; however, the lack of direct electrical contacts dramatically hinders the corresponding field-driven control and applications. Here, the formation of electric-field-switchable Néel-type polar skyrmions at room temperature is demonstrated in Ba0.8Sr0.2TiO3 (BSTO) thin films directly grown on metallic SrRuO3 electrodes. In this study, strategic Sr substitution is employed to engineer the Landau energy landscape of ferroelectric material BaTiO3, which eventually facilitates the coexistence of multiple polarization states without sacrificing room-temperature ferroelectricity. Piezoelectric force microscopy (PFM) uncovers a critical BSTO thickness to host the phenomena: conventional ferroelectric domains dominate 60-nm thick BSTO, whereas high-density topological polar textures emerge in 10-nm thick BSTO. Specifically, vector-PFM analysis identifies two stable skyrmion states in 10-nm BSTO with convergent- and divergent- in-plane polarization components. Importantly, an electric-field-driven interconversion between these topological states is demonstrated by reconfiguring the free-energy landscape, which is also supported by the phase-field simulations. This work provides a direct pathway of using metallic electrodes for the dynamic control of topological ferroelectrics in functional devices.
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Nov 2025
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I19-Small Molecule Single Crystal Diffraction
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Esther Y. H.
Hung
,
Benjamin M.
Gallant
,
Robert
Harniman
,
Jakob
Moebs
,
Santanu
Saha
,
Khaled
Kaja
,
Charles
Godfrey
,
Shrestha
Banerjee
,
Nikolaos
Famakidis
,
Harish
Bhaskaran
,
Marina R.
Filip
,
Paolo
Radaelli
,
Nakita K.
Noel
,
Dominik J.
Kubicki
,
Harry C.
Sansom
,
Henry J.
Snaith
Diamond Proposal Number(s):
[36669]
Open Access
Abstract: Molecular piezoelectrics are a potentially disruptive technology, enabling a new generation of self-powered electronics that are flexible, high performing, and inherently low in toxicity. Although significant efforts have been made toward understanding their structural design by targeted manipulation of phase transition behavior, the resulting achievable piezoresponse has remained limited. In this work, we use a low-symmetry, zero-dimensional (0D) inorganic framework alongside a carefully selected ‘quasi-spherical’ organic cation to manipulate organic–inorganic interactions and thus form the hybrid, piezoelectric material [(CH3)3NCH2I]3Bi2I9. Using variable–temperature single crystal X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy, we demonstrate that this material simultaneously exhibits an order–disorder and displacive symmetry-breaking phase transition. This phase transition is mediated by halogen bonding between the organic and inorganic frameworks and results in a large piezoelectric response, d33 = 161.5 pm/V. This value represents a 4-fold improvement on previously reported halobismuthate piezoelectrics and is comparable to those of commercial inorganic piezoelectrics, thus offering a new pathway toward low-cost, low-toxicity mechanical energy harvesting and actuating devices.
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Nov 2025
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B23-Circular Dichroism
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Mateusz
Pawlak
,
Julia
Abramowicz
,
Nadesh
Fiuza Maneiro
,
Gail A.
Vinnacombe-Willson
,
Sunghwan
Jo
,
Elie
Benchimol
,
Piotr
Roszkowski
,
Zitao
Chen
,
Da
Wang
,
Guido H.
Clever
,
Luis M.
Liz-Marzán
,
Agustín
Mihi
,
Lakshminarayana
Polavarapu
,
Wiktor
Lewandowski
Diamond Proposal Number(s):
[34852, 38639]
Open Access
Abstract: Perovskite nanocrystals (PNCs) exhibiting circularly polarized luminescence (CPL) represent a promising class of materials for display and light communication technologies, owing to their emission covering the entire visible range with near-unity photoluminescence efficiency. However, these materials suffer from low selectivity in the handedness of the emitted light, with most studies focusing on green emission. We address these issues by exploiting and broadening the scope of interactions between achiral PNCs and chiral organic templates. For this purpose, we select three types of PNCs with red, green, and blue emissions and introduce them into a chiral liquid-crystalline matrix in the form of composite thin films. Electron microscopy confirmed the assembly of PNCs within nanoscale gaps formed by supramolecular, liquid crystalline structures. The obtained composites displayed a CPL dissymmetry factor glum up to ≈ 0.24. The highly dissymmetric CPL properties were found to result from an interplay between two effects: chiral assembly of PNCs within a chiral environment (intrinsic) and the selective filtering by the chiral matrix. This system enables control over the dominant factors by adjusting the CPL spectral region and type of particle assembly, providing thin film materials with highly dissymmetric and spectrally tunable CPL responses.
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Nov 2025
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B23-Circular Dichroism
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Francesco
Furlan
,
Michal
Šámal
,
Jiří
Rybáček
,
Andrea
Taddeucci
,
Marta
Di Girolamo
,
Davide
Nodari
,
Giuliano
Siligardi
,
Jessica
Wade
,
Binghai
Yan
,
Irena G.
Stará
,
Nicola
Gasparini
,
Matthew J.
Fuchter
Diamond Proposal Number(s):
[32632]
Open Access
Abstract: The photon spin information encoded in circularly polarized (CP) light is of high interest for current and future technologies, including low-power displays, encrypted communications and high-performance quantum applications. Engineering organic light-emitting diodes (LED) to emit oppositely handed electroluminescent CP light typically requires access to left- and right-handed chiral molecules. In conjugated polymer LEDs, the handedness of CP electroluminescence also depends on the active-layer thickness or direction of current flow. For a given active-layer thickness, it remains unknown whether a single-handed chiral material can emit CP light with opposite handedness in the same LED architecture. Here we demonstrate organic LEDs in which the handedness of the emitted CP electroluminescence can be controlled electrically, solely by using specific interlayers with no change in the emissive material composition or thickness. We reveal that this occurs due to a change in mechanism for the generation of CP electroluminescence, as a function of the recombination zone position within the device. This result provides a paradigm shift in the realization of organic CP-LEDs with controllable spin angular momentum information and further contributes to ongoing discussions relating the fundamental physics of chiral optoelectronics.
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Nov 2025
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I06-Nanoscience (XPEEM)
I10-Beamline for Advanced Dichroism - scattering
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Di
Tian
,
Haotian
Zheng
,
Zewei
Huang
,
Sijie
Wu
,
Pengcheng
Li
,
Cong
Li
,
Jianbing
Zhang
,
Xinyu
Shu
,
Jinling
Zhou
,
Yang
Liu
,
Yanhong
Gu
,
Meng
Wang
,
Di
Yi
,
Tianxiang
Nan
,
Zhen
Chen
,
Qing
He
,
Huaqiang
Wu
,
Shuyun
Zhou
,
Weidong
Luo
,
Pu
Yu
Open Access
Abstract: Layered oxide materials, with their two-dimensional crystalline architectures and tunable interlayer interaction, serve as a fertile field for harnessing emergent quantum phenomena. Among these materials, metallic delafossites (e.g., PdCoO2) have emerged as a prominent system with extraordinary two-dimensional electronic properties, though their intrinsic lack of ferromagnetism has remained a fundamental constraint. Here, we report the creation of robust, bulk high-temperature ferromagnetism (𝑇𝑐>420 K) in inherently nonmagnetic PdCoO2 through controlled hydrogenation while preserving the delafossite structure. This process induces layer-selective electron doping into CoO2 layers, stabilizing Ising-type ferromagnetism with pronounced perpendicular magnetic anisotropy while preserving the material’s exceptional metallicity. Remarkably, the system self-assembles into a superlattice of alternating metallic Pd and insulating ferromagnetic hydrogenated CoO2 layers, enabling an unconventional anomalous Hall effect mediated by interlayer spin-charge coupling. These findings demonstrate that bulk ferromagnetism can be achieved in delafossite oxides while preserving their structural integrity, positioning hydrogenated delafossites as a versatile platform for exploring correlated quantum effects and designing multifunctional devices.
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Nov 2025
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I07-Surface & interface diffraction
I15-Extreme Conditions
I19-Small Molecule Single Crystal Diffraction
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Yang
Lu
,
Young-Kwang
Jung
,
Milos
Dubajic
,
Xinjuan
Li
,
Shabnum
Maqbool
,
Qichun
Gu
,
Xinyu
Bai
,
Yorrick
Boeije
,
Xian Wei
Chua
,
Alessandro J.
Mirabelli
,
Taeheon
Kang
,
Lars
Sonneveld
,
Youcheng
Zhang
,
Thomas A.
Selby
,
Capucine
Mamak
,
Kan
Tang
,
Zhongzheng
Yu
,
Tianjun
Liu
,
Miguel
Anaya
,
Stephen
Barlow
,
Seth R.
Marder
,
Bruno
Ehrler
,
Caterina
Ducati
,
Richard H.
Friend
,
Samuel D.
Stranks
Diamond Proposal Number(s):
[32266, 38601, 30043, 33123, 36628, 38508]
Abstract: Halide perovskites exhibit superior optoelectronic properties but lack precise thickness and band offset control in heterojunctions, which is critical for modular multilayer architectures such as multiple quantum wells. We demonstrate vapor-phase, layer-by-layer heteroepitaxial growth exemplified by CsPbBr3 deposition on single crystals of PEA2PbBr4 (PEA: 2-phenylethylammonium). Angstrom-level thickness control and subangstrom smooth layers enable quantum-confined photoluminescence of CsPbBr3 from monolayer, bilayer, and through to bulk. The interfacial structure controls the electronic structure from a Cs‒PEA-terminated interface (type II heterojunction) to a PEA‒PEA-terminated interface (type I heterojunction), with a layer-tunable band offset shift exceeding 0.5 electron volts. Electron transfer from CsPbBr3 to PEA2PbBr4 for a type II Cs‒PEA heterojunction results in delayed electron-hole recombination beyond 10 microseconds. Precise quantum confinement control and large band offset tunability unlock perovskite heterojunctions as platforms for scalable, superlattice-based optoelectronic applications.
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Nov 2025
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I07-Surface & interface diffraction
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Zhongzheng
Yu
,
Yunzhou
Deng
,
Junzhi
Ye
,
Lars
Van Turnhout
,
Tianjun
Liu
,
Alasdair
Tew
,
Rakesh
Arul
,
Simon
Dowland
,
Yuqi
Sun
,
Xinjuan
Li
,
Linjie
Dai
,
Caterina
Ducati
,
Jeremy J.
Baumberg
,
Richard H.
Friend
,
Robert L. Z.
Hoye
,
Akshay
Rao
Diamond Proposal Number(s):
[32266]
Open Access
Abstract: Insulating nanomaterials have large energy gaps and are only electrically accessible under extreme conditions, such as high-intensity radiation and high temperature, pressure or voltage1,2. Lanthanide-doped insulating nanoparticles (LnNPs) are widely studied owing to their exceptional luminescence properties, including bright, narrow-linewidth, non-blinking and non-bleaching emission in the second near-infrared (NIR-II) range3,4. However, it has not been possible to electrically generate excited states in these insulating nanomaterials under low biases and, therefore, not possible to fabricate optoelectronic devices from these systems. Here we report an electrical excitation pathway to obtain emission from LnNPs. By forming LnNP@organic molecule nanohybrids, in which the recombination of electrically injected charges on the organic molecule is followed by efficient triplet energy transfer (TET) to the LnNP, it is possible to turn on LnNPs under a low operating bias. We demonstrate this excitation pathway in light-emitting diodes (LEDs), with low turn-on voltages of about 5 V, very narrow electroluminescence (EL) spectra and a peak external quantum efficiency (EQE) greater than 0.6% in the NIR-II window5. Our LnNP-based LEDs (LnLEDs) also allow for widely tunable EL properties, by changing the type and concentration of lanthanide dopants. These results open up a new field of hybrid optoelectronic devices and provide new opportunities for the electrically driven excitation sources based on lanthanide nanomaterials for biomedical and optoelectronic applications.
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Nov 2025
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I09-Surface and Interface Structural Analysis
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Han
Yan
,
Yan
Wang
,
Yang
Li
,
Dibya
Phuyal
,
Lixin
Liu
,
Hailing
Guo
,
Yuzheng
Guo
,
Tien-Lin
Lee
,
Minhyuk
Kim
,
Hu Young
Jeong
,
Manish
Chhowalla
Diamond Proposal Number(s):
[30105, 33391, 32963, 38086]
Open Access
Abstract: Two-dimensional transition metal dichalcogenide semiconductors possess ideal attributes for meeting industry scaling targets for transistor channel technology. However, the development of scaled field-effect transistors (FETs) requires industry-compatible gate dielectrics with low equivalent oxide thicknesses. Here we show that zirconium oxide (ZrO2)—an industry-compatible high-dielectric-constant (k) oxide—can form a clean interface with two-dimensional molybdenum disulfide (MoS2). Photoelectron spectroscopy analysis shows that although silicon dioxide and hafnium oxide substrates introduce the doping of MoS2, ZrO2 exhibits no measurable interactions with MoS2. Back-gated monolayer MoS2 FETs using ZrO2 as a dielectric exhibit stable and positive threshold voltages of 0.36 V, subthreshold swings of 75 mV dec−1 and ON currents of more than 400 µA. We also use ZrO2 dielectrics to fabricate p-type tungsten diselenide FETs with ON-state currents of more than 200 µA µm−1. Atomic-resolution imaging of ZrO2 deposited on top of MoS2 reveals a defect-free interface, which leads to top-gated FETs with an equivalent oxide thickness of 0.86 nm and subthreshold swing values of 80 mV dec−1. The clean interface between ZrO2 and monolayer MoS2 allows the effective modulation of threshold voltage in top-gated FETs via gate metal work-function engineering.
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Oct 2025
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I10-Beamline for Advanced Dichroism - scattering
I21-Resonant Inelastic X-ray Scattering (RIXS)
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Andrey D.
Poletayev
,
Robert J.
Green
,
Jack E. N.
Swallow
,
Lijin
An
,
Leanne
Jones
,
Grant
Harris
,
Peter
Bencok
,
Ronny
Sutarto
,
Jonathon P.
Cottom
,
Benjamin J.
Morgan
,
Robert A.
House
,
Robert S.
Weatherup
,
M. Saiful
Islam
Diamond Proposal Number(s):
[33062, 30644]
Open Access
Abstract: Nickelate materials offer diverse functionalities for energy and computing applications. Lithium nickel oxide (LiNiO2) is an archetypal layered nickelate, but the electronic structure of this correlated material is not yet fully understood. Here we investigate the temperature-dependent speciation and spin dynamics of Ni ions in LiNiO2. Ab initio simulations predict that Ni ions disproportionate into three states, which dynamically interconvert and whose populations vary with temperature. These predictions are verified using x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and resonant inelastic x-ray scattering at the Ni L3,2-edge. Charge-transfer multiplet calculations consistent with disproportionation reproduce all experimental features. Our results support a model of dynamic disproportionation that explains diverse physical observations of LiNiO2, including magnetometry, thermally activated electronic conduction, diffractometry, core-level spectroscopies, and the stability of ubiquitous antisite defects. This unified understanding of the material properties of LiNiO2 is important for applications of nickelate materials as battery cathodes, catalysts, and superconductors.
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Oct 2025
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