I06-Nanoscience (XPEEM)
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Weican
Lan
,
Chaocheng
Liu
,
Yajuan
Feng
,
Ruiqi
Liu
,
Yafei
Chu
,
Lu
Cheng
,
Chao
Wang
,
Huijuan
Wang
,
Minghui
Fan
,
Zixun
Zhang
,
Yuran
Niu
,
Jheng-Cyuan
Lin
,
Francesco
Maccherozzi
,
Hengli
Duan
,
Wensheng
Yan
Diamond Proposal Number(s):
[40612]
Abstract: Excitons are primary elementary excitations in solids that present both fundamental interest and technological importance, showing great potential for photospintronic and quantum transduction applications. The emerging coherent collective excitations in two-dimensional antiferromagnetic semiconductors raise prospects for spin-exciton interactions and multifield control schemes. However, realizing the arbitrary manipulation of excitonic quantum states, while preserving the inherent dynamic and response advantages of antiferromagnetic nature remains challenging. Here we achieve bidirectional modulation of the CrSBr exciton energy via interfacial interaction-modified spin-exciton coupling in a CrSBr/Fe3GaTe2 heterostructure. Compared with pristine CrSBr, the photoluminescence peaks in the heterostructure can exhibit blueshift and redshift corresponding to 6.1% and 8.6% of the total bandwidth, respectively. We reveal that the interfacial charge-transfer-driven magnetic coupling in the heterostructure effectively enhances the magnetic anisotropy and the exchange interaction of CrSBr, thereby stabilizing its antiferromagnetic spin configuration, suppressing interlayer electron-hole recombination, and ultimately leading to an anomalous blueshift of the exciton emission. Our findings demonstrate an approach for bidirectionally modulating exciton energy in two-dimensional antiferromagnetic semiconductors, which provides substantial flexibility in device design and offers an avenue for potential wavelength control in quantum information and optoelectronic technologies.
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Feb 2026
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[32893]
Open Access
Abstract: The crystal and magnetic structures of Sr3Fe4O6S2 (= Sr3Fe2O5Fe2OS2) and Sr4Fe4O7S2 (= Sr4Fe2O6Fe2OS2), designed using a building-block approach, are reported. They are fully charge-ordered with Fe2+ and Fe3+ ions in distinct layers showing independent long-range magnetic order. Complex microstructures in some regions suggest new targets.
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Feb 2026
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I19-Small Molecule Single Crystal Diffraction
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Cara J.
Hawkins
,
Batoul
Almoussawi
,
Jan P.
Scheifers
,
Manel
Sonni
,
Aeshah A.
Almushawwah
,
Troy D.
Manning
,
Marco
Zanella
,
Craig M.
Robertson
,
Luke M.
Daniels
,
Tim D.
Veal
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[36629]
Open Access
Abstract: The exploration of higher-dimensional chemical phase spaces and the synthesis of novel compounds can be achieved by applying a multiple-anion approach to materials discovery. The ability to combine and tune the stoichiometry of anions in a material can enable enhanced control of both the physical and electronic structures, providing a strategy for the modification of the properties of new materials being developed for a variety of applications, including solar absorbers and thermoelectrics. Here, we report the synthesis of Cu7.62Bi6Se12Cl6I, a quadruple-anion (Se2–, (Se2)2–, Cl–, I–) material within the Cu–Bi–Se–Cl–I phase space. Crystal growth reactions yield black, needle-like crystals, which exhibit a highly anisotropic and complex structure containing the four distinct anion types, solved from single-crystal X-ray diffraction data. Compositional analysis confirms the complex material stoichiometry, and a low band gap of 0.94(5) eV is measured to understand the potential for solar-absorbing applications. Cu7.62Bi6Se12Cl6I has a low thermal conductivity of 0.25(2) W K–1 m–1, which is attributed to multiple structural features via analysis of experimental heat capacity data and is achieved through the diversity in bonding that is accessed through the combination of four different types of anion.
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Feb 2026
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Emily C.
Mcfarlane
,
Antonio
Sanna
,
Matthew J.
Gilbert
,
Jonas A.
Krieger
,
Mihir
Date
,
Gabriele
Domaine
,
Banabir
Pal
,
Anirban
Chakraborty
,
Pranava K.
Sivakumar
,
Procopios C.
Constantinou
,
Anna
Hartl
,
Enrico G.
Della Valle
,
Camilla
Pellegrini
,
Vladimir N.
Strocov
,
Stuart S. P.
Parkin
,
Niels B. M.
Schroeter
Open Access
Abstract: Superconductivity in the transition-metal dichalcogenide PdTe2 has been attributed to the proximity of a three-dimensional Van Hove singularity to the Fermi level. In isostructural NiTe2, recently used as the weak link in a Josephson diode, a similar Van Hove singularity has been predicted to occur, but superconductivity is mysteriously absent. Using bulk-sensitive soft x-ray angle-resolved photoemission spectroscopy, we reveal that this Van Hove singularity lies even closer to the Fermi level in NiTe2 than in PdTe2. To explain the lack of superconductivity in NiTe2, we perform ab initio calculations incorporating the Kukkonen Overhauser interaction, showing that an incipient magnetic instability suppresses superconductivity at an unprecedented scale. Finally, we present a tight-binding model that links the Van Hove singularity to a sign change in the Josephson diode effect at small magnetic fields, suggesting a new mechanism for Josephson diodes.
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Feb 2026
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I09-Surface and Interface Structural Analysis
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Trung-Phuc
Vo
,
Olena
Tkach
,
Aki
Pulkkinen
,
Didier
Sébilleau
,
Aimo
Winkelmann
,
Olena
Fedchenko
,
Yaryna
Lytvynenko
,
Dmitry
Vasilyev
,
Hans-Joachim
Elmers
,
Gerd
Schoenhense
,
Jan
Minar
Diamond Proposal Number(s):
[33765]
Open Access
Abstract: The intricate fine structure of Kikuchi diffraction plays a vital role in probing phase transformations and strain distributions in functional materials, particularly in electron microscopy. Beyond these applications, it also proves essential in photoemission spectroscopy (PES) at high photon energies, aiding in the disentanglement of complex angle-resolved PES data and enabling emitter-site-specific studies. However, the detection and analysis of these rich faint structures in photoelectron diffraction, especially in the hard x-ray regime, remain highly challenging, with only a limited number of simulations successfully reproducing these patterns. The strong energy dependence of Kikuchi patterns further complicates their interpretation, necessitating advanced theoretical approaches. To enhance structural analysis, we present a comprehensive theoretical study of fine diffraction patterns and their evolution with energy by simulating core-level emissions from Ge(100) and Si(100). Using multiple-scattering theory and the fully relativistic one-step photoemission model, we simulate faint pattern networks for various core levels across different kinetic energies (106–4174 eV), avoiding cluster size convergence issues inherent in cluster-based methods. Broadening in patterns is discussed via the inelastic scattering treatment. For the first time, circular dichroism has been observed and successfully reproduced in the angular distribution of Si(100) 1𝑠, revealing detailed features and asymmetries up to 31%. Notably, we successfully replicate experimental bulk and more “surface-sensitivity” diffraction features, further validating the robustness of our simulations. The results show remarkable agreement with the experimental data obtained using circularly polarized radiations, demonstrating the potential of this methodology for advancing high-energy PES investigations.
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Feb 2026
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I05-ARPES
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Oliver J.
Clark
,
Anugrah
Azhar
,
Thi-Hai-Yen
Vu
,
Benjamin A.
Chambers
,
Federico
Mazzola
,
Sadhana
Sridhar
,
Geetha
Balakrishnan
,
Aaron
Bostwick
,
Chris
Jozwiak
,
Eli
Rotenberg
,
Sarah L.
Harmer
,
Mohammad Saeed
Bahramy
,
Michael S.
Fuhrer
,
Mark T.
Edmonds
Diamond Proposal Number(s):
[40610]
Open Access
Abstract: Discovering and engineering spin-polarized surface states in the electronic structures of condensed matter systems is a crucial first step in the development of spintronic devices, wherein spin-polarized bands crossing the Fermi level can facilitate information transfer. Here, through nanofocused angle-resolved photoemission spectroscopy (nano-ARPES) and density functional theory-based calculations, we show that the interface between monolayer WSe2 and metallic NbSe2 exhibits a negative Schottky barrier height of ∼ −30 meV: the K-point valleys of the semiconducting layer are shifted by ∼800 meV to produce a surface-localized Fermi surface populated only by spin-polarized charge carriers. By increasing the WSe2 thickness, the Fermi pockets can be moved from K to Γ, demonstrating tunability of novel semimetallic phases that exist atop a substrate additionally possessing charge density wave and superconducting phases. Together, this study provides a spectroscopic understanding into p-type, Schottky barrier-free interfaces, which are of urgent interest for bypassing the limitations of current-generation vertical field effect transistors, in addition to longer-term spintronics development.
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Feb 2026
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Abstract: Fe-based pnictides have evolved as a practical alternative to Cuprate superconductors. Electrons are transported along As–Fe–As path of inter-connected FeAs4, utilizing Fe 3d-As 4p orbital hybridization. This leads to an obvious question — what are the key tetrahedral parameters that control hybridization? Unfortunately, empirical results from discrete experiments generated conflicting structure-transport correlations. The present work attempts to fill this logistic gap by probing the missing structure-orbital correlation link. To this effect, pressure-dependent XRD and As K-edge XANES were measured on the same sample set of PrOFe
0
.
9
Co
0
.
1
As. A point of inflection emerges at the compressibility limit of Fe–As bond-length. At this point, the trajectory of As atom and (correspondingly) parameters of FeAs4 undergo parabolic reversal whilepd hybridization undergoes nonreversible maximization. This incongruence generates nonlinear structure-orbital correlation, which is a novel finding. Two novel concepts emanate from this exercise — (a) compressibility limit of Fe–As bond-length emerges as the new critical reference and (b) nonlinearity warrants that pd hybridization is sensitive to the phase of As trajectory (relative to this reference) rather than the absolute values of tetrahedral parameters. These mark major corrections from previous works, which should settle the existing conflicts.
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Feb 2026
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Gesa-R.
Siemann
,
Davide
Curcio
,
Anders S.
Mortensen
,
Charlotte E.
Sanders
,
Yu
Zhang
,
Jennifer
Rigden
,
Paulina
Majchrzak
,
Deepnarayan
Biswas
,
Emma
Springate
,
Ratnadwip
Singha
,
Leslie M.
Schoop
,
Philip
Hofmann
Abstract: Optical control offers a compelling route for tailoring material properties on an ultrafast time scale. Ordered states such as charge density waves (CDWs) can be transiently melted by an ultrafast light excitation. This is also the case for the rare-earth tritelluride LaTe3, a prototypical CDW compound. For this material it has recently been reported that the suppression of the primary CDW allows the transient formation of a second CDW, whose wave vector is orthogonal to the primary one. This creates the intriguing scenario where light enables switching between two distinct ordered phases of the material. While the second CDW has so far been observed by structural techniques, it remains an open question how the interplay of the two CDW phases is reflected in the material's electronic structure. We investigate this via time- and angle-resolved photoemission measurements of LaTe3. The complex Fermi contour is probed using a FeSuMa analyzer, which records the photoemission intensity of the entire Fermi contour at once. The dynamics revealed by the FeSuMa analyzer are complemented by measurements using a conventional hemispherical electron analyzer. We combine conventional data analysis with 𝑘-means clustering, an unsupervised machine learning technique, demonstrating its strong potential for disentangling large datasets. While we do not find any features that cannot be explained by the melting and reestablishment of the primary CDW, distinct dynamics and coherent oscillations are observed in the different branches of the Fermi contour.
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Feb 2026
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[36624, 38372]
Open Access
Abstract: Binary mixtures of the ferronematic liquid crystal DIO with the recently reported LC non-ferroelectric material WJ-16 exhibiting Colossal Permittivity (CP) ≈ 5000 and superparaelectricity were studied by POM, electrical switching studies, and dielectric spectroscopy. Three mixtures with different WJ-16 contents ranging from 10, 25 to 50% (w/w) in DIO as host were prepared. Our original expectation was the observations of new nematic compositions with both ferroelectric nematic (N F ) and non-ferroelectric CP phases. We found that the non-ferroelectric phase in mixtures exhibits a CP mode, originally observed in pure WJ-16. The dielectric spectroscopy of mixtures shows two distinct relaxation processes: the typical paraelectric response and the CP mode. Therefore, this CP mode in the mixtures is not superparaelectric and here it is defined as a Hyper-dielectric mode. This is the first direct demonstration of mixtures having both ferroelectric and hyper-dielectric phases in liquid crystalline materials.
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Feb 2026
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Oliver J.
Clark
,
Anugrah
Azhar
,
Ben A.
Chambers
,
Daniel
Mcewen
,
Thi-Hai-Yen
Vu
,
Mohammad T.h.
Bhuiyan
,
Rodion V.
Belosludov
,
Aaron
Bostwick
,
Chris
Jozwiak
,
Eli
Rotenberg
,
Seng Huat
Lee
,
Zhiqiang
Mao
,
Geetha
Balakrishnan
,
Federico
Mazzola
,
Sarah L.
Harmer
,
Michael S.
Fuhrer
,
Mohammad Saeed
Bahramy
,
Mark T.
Edmonds
Open Access
Abstract: Van der Waals materials enable the construction of atomically sharp interfaces between compounds with distinct crystal and electronic properties. This is dramatically exploited in moiré systems, where a lattice mismatch or twist between monolayers generates an emergent in-plane periodicity, giving rise to electronic properties absent in the constituent materials. In contrast, vertical superlattices, formed by stacking dissimilar materials in the out-of-plane direction on the nanometer scale, have received far less attention despite their potential to realize analogous emergent phenomena in three dimensions. Through angle-resolved photoemission spectroscopy and density functional theory, we investigate six-to-eight-layer transition metal dichalcogenide (TMD) heterostructures constructed from pairs of stacked few-layer materials. Counterintuitively, we find that even these single superlattice units can host fully delocalized bands, evidencing a robust coherent interlayer coupling across lattice-mismatched interfaces over extended spatial scales. We show how uncompensated semimetallic phases and energetically mismatched topological surface states are readily and exclusively stabilized within such asymmetrical architectures. These findings establish two-component heterostructures in the intermediate-layer regime as platforms to invoke and control unprecedented combinations and instances of the diverse quantum phases native to many-layer TMDs.
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Feb 2026
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