I10-Beamline for Advanced Dichroism - scattering
|
Roxana
Capu
,
Ryan
Thompson
,
C. Willem
Rischau
,
Marli R.
Cantarino
,
Premysl
Marsik
,
Sergey L.
Bud'Ko
,
Neven
Biškup
,
María
Varela
,
Yurii G.
Pashkevich
,
Serhii M.
Orel
,
Thomas
Prokscha
,
Andreas
Suter
,
Jiangtao
Zhao
,
Ugwumsinachi
Oji
,
Marco
Bonura
,
Peter
Bencok
,
Zaher
Salman
,
Stefano
Gariglio
,
Christian
Bernhard
,
Subhrangsu
Sarkar
Diamond Proposal Number(s):
[38112]
Open Access
Abstract: We report the dielectric and magnetic properties of epitaxial thin films of the high entropy oxide (HEO) perovskite Nd(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3, which orders magnetically below Tmag≈190 K. At T ≫ Tmag, the dielectric response reveals a Debye-type frequency dependence with a zero-frequency dielectric constant of
≈230–250. The dc bias voltage loops of
are reversible but exhibit three distinct peaks centred at zero and finite positive and negative voltage. We provide evidence that the zero-bias peak is governed by the oxygen sublattice while the finite bias peaks originate from cationic dipoles. The maximal response of the latter appears to be shifted to finite bias by a static uncompensated electric field due to a vertical gradient of the oxygen content. Below Tmag, this anomalous dielectric response is strongly suppressed, presumably by magnetostriction that counteracts and freezes the ionic displacements. These findings indicate a unique correlation between configurational entropy, dielectric response, and magnetic properties. In combination with a large dielectric strength, it enables a non-hysteretic tuning of the dielectric response of magnetoelectronic devices with multiple parameters like temperature, electric, and magnetic field. This HEO is equally interesting for fundamental studies of competing electric and magnetic orders in strongly disordered materials.
|
Apr 2026
|
|
I15-Extreme Conditions
|
Zhencai
Li
,
Zihao
Wang
,
Huotian
Zhang
,
Xuan
Ge
,
Ivan
Hung
,
Bozhao
Yin
,
Fengming
Cao
,
Pritam
Banerjee
,
Tianzhao
Xu
,
Lars R.
Jensen
,
Joerg
Jinschek
,
Morten M.
Smedskjaer
,
Zhehong
Gan
,
Laurent
Calvez
,
Guoping
Dong
,
Jianbei
Qiu
,
Donghong
Yu
,
Feng
Gao
,
Haomiao
Zhu
,
Yuanzheng
Yue
Diamond Proposal Number(s):
[39002]
Open Access
Abstract: Some zeolitic imidazolate frameworks (ZIFs) represent a new family of glass formers, with hitherto unknown photonic functionalities. In this work, we report the discovery of broadband white light emission in ZIF-62, achieved through a vitrification-pressurization-annealing strategy. In this strategy, visible (blue) light emission was realized after the vitrification of ZIF-62, subsequently enhanced and broadened upon pressurization. Additionally, a sharp redshift (37 nm) of the emission peak occurred in pressurized ZIF-62 glass as the annealing temperature exceeded a critical annealing temperature (1.07Tg). This implies that the photoluminescence of ZIF-62 can be precisely tailored. The photoluminescence quantum yield of ZIF-62 glass reached 12.2% after annealing at 1.13Tg for 30 min. The origin of the observed phenomena was revealed by conducting structural analyses. Based on the annealed ZIF-62 glass with the best photoluminescent performance, a white light-emitting diode (LED) was fabricated, which exhibited a luminous efficacy of 4.2 lm/W and a high operational stability, i.e., retaining 36.8% of the efficacy after 72 h of operation. This work demonstrated the feasibility of the development of one-component white LEDs by utilizing the annealed ZIF-62 glass.
|
Mar 2026
|
|
I09-Surface and Interface Structural Analysis
|
Lixin
Liu
,
Han
Yan
,
Leyi
Loh
,
Kamal Kumar
Paul
,
Soumya
Sarkar
,
Deepnarayan
Biswas
,
Tien-Lin
Lee
,
Takashi
Taniguchi
,
Kenji
Watanabe
,
Manish
Chhowalla
,
Yan
Wang
Diamond Proposal Number(s):
[38012, 39914]
Open Access
Abstract: Excellent gate electrostatics in field effect transistors (FETs) based on 2D transition metal dichalcogenide (2D TMD) channels can dramatically decrease static power dissipation. Energy-efficient FETs operate in enhancement mode with a small and positive threshold voltage (Vth) for n-type devices. However, most state-of-the-art FETs based on monolayer MoS2 channel operate in depletion mode with negative Vth due to doping from the underlying dielectric substrate. In this work, we identify key properties of the semiconductor/dielectric interface (MoS2 on industrially relevant high dielectric constant (k) HfO2, ZrO2 and hBN for reference) responsible for realizing enhancement-mode operation of 2D MoS2 channel FETs. We find that hBN and ZrO2 dielectric substrates provide low defect interfaces with MoS2 that enables effective modulation of the Vth using gate metals of different work functions (WFs). We use photoluminescence (PL) and synchrotron X-ray photoelectron spectroscopy (XPS) measurements to investigate doping levels in monolayer MoS2 on different dielectrics with different WF gate metals. We complement the FET and spectroscopic measurements with capacitance-voltage analysis on dielectrics with varying thicknesses, which confirms that Vth modulation in ZrO2 devices is correlated with WF of the gate metals – in contrast with HfO2 devices that exhibit signatures of Vth pinning induced by oxide/interface defect states. Finally, we demonstrate FETs using a 2D MoS2 channel and a 6 nm of ZrO2 dielectric, achieving a subthreshold swing of 87 mV dec−1 and a threshold voltage of 0.1 V. Our results offer insights into the role of dielectric/semiconductor interface in 2D MoS2 based FETs for realizing enhancement mode FETs and highlight the potential of ZrO2 as a scalable high-k dielectric.
|
Mar 2026
|
|
I11-High Resolution Powder Diffraction
|
Ziqin
Jiao
,
Tao
Zeng
,
Wenhai
Ji
,
Zheng
Liu
,
Wenguang
Zhao
,
Xiaoyu
Gao
,
Yongbiao
Mu
,
Xuansi
Jiang
,
Yubin
Li
,
Guojie
Chen
,
Wenqing
Yao
,
Jinqi
Li
,
Ze
He
,
Juping
Xu
,
Ping
Miao
,
Wen
Yin
,
Yuguang
Pu
,
Rui
Wang
,
Yinguo
Xiao
Diamond Proposal Number(s):
[34243]
Abstract: Lattice-oxygen redox (L-OR) has been widely considered a viable approach to attain high-capacity cathodes for next-generation batteries. However, achieving highly reversible L - OR remains challenging due to the intrinsic chemical instability of lattice oxygen. As such, stabilizing the lattice oxygen becomes necessary for improving the performance of cathode materials with oxygen redox chemistry. In this study, the distinct properties of both bulk and surface lattice oxygen are systematically studied in a model Li-rich layered oxide material (LRMO, i.e., Li1.2Ni0.2Mn0.6O2) by employing different techniques. We find that, in the bulk, distortions in octahedral coordination geometry are closely correlated with variations in the electronic structure, and the substitution of Li ions with protons in a subsurface layer enhances the stability of surface lattice oxygen by altering its coordination environment. By jointly regulating the local environments of both bulk and surface lattice oxygen, the initial Coulombic efficiency is remarkably improved from 73.88% to 91.72%. Moreover, the modified LRMO demonstrates an impressive cycle stability, which realizes a capacity retention of 95.9% after 500 cycles at 250 mA g−1. This work demonstrates that rationally-designed local environments of lattice oxygen can effectively stabilize the oxygen redox in Li-rich cathodes.
|
Feb 2026
|
|
Optics
|
Arindam
Majhi
,
Wadwan
Singhapong
,
Wai Jue
Tan
,
Andrey
Sokolov
,
Stefano
Agrestini
,
Mirian
Garcia-Fernandez
,
Ke-Jin
Zhou
,
Andrew C.
Walters
,
Chris
Bowen
,
Alexander J. G.
Lunt
,
Hongchang
Wang
,
Kawal J.
Sawhney
Open Access
Abstract: Laterally graded multilayer optics play an important role in advanced X-ray applications, enabling precise control of beam properties for spectroscopic and focusing techniques. The Multilayer Deposition System (MDS) at Diamond Light Source (DLS) has demonstrated its ability to fabricate highly precise laterally graded X-ray optics. Developing such optics is challenging due to stringent requirements for precise lateral thickness variations and sagittal uniformity, achieved through optimized substrate speed profiles and advanced mask design. This study presents a comprehensive investigation into the design, fabrication, and characterization of laterally graded multilayers. An adjustable mask design improves sagittal uniformity and reduces optimization times. The structural and optical performance of the multilayers is evaluated, confirming their suitability for synchrotron applications. Two types of laterally graded multilayers were developed: one with a constant lateral gradient (0.005 nm/mm) for O-K edge polarizers, achieving sagittal thickness variations of approximately 0.3–0.4% across an 80 mm substrate, and another featuring a strong variable gradient from 0.037 to 0.112 nm/mm, designed to match the elliptical periodicity profile. The constant gradient multilayer polarizer has been successfully implemented on the state-of-the-art I21 beamline at DLS, highlighting the MDS's role in producing next-generation X-ray optics that meet the stringent demands of synchrotron beamlines.
|
Jan 2026
|
|
I05-ARPES
|
Shu
Mo
,
Ksenija
Kovalenka
,
Sebastian
Buchberger
,
Bruno K.
Saika
,
Anugrah
Azhar
,
Akhil
Rajan
,
Andela
Zivanovic
,
Yu-Chi
Yao
,
Rodion V.
Belosludov
,
Matthew D.
Watson
,
M. Saeed
Bahramy
,
Phil D. C.
King
Diamond Proposal Number(s):
[36192]
Open Access
Abstract: Moiré heterostructures, created by stacking 2D materials together with a finite lattice mismatch or rotational twist, represent a new frontier of designer quantum materials. Typically, however, this requires the painstaking manual assembly of heterostructures formed from exfoliated materials. Here, clear spectroscopic signatures of moiré lattice formation in epitaxial heterostructures of monolayer (ML) NbSe2 grown on graphite substrates are observed. Angle-resolved photoemission measurements and theoretical calculations of the resulting electronic structure reveal moiré replicas of the graphite π states forming pairs of interlocking Dirac cones. Interestingly, these intersect the NbSe2 Fermi surface at the -space locations where NbSe2's charge-density wave (CDW) gap is maximal in the bulk. This provides a natural route to understand the lack of CDW enhancement for ML-NbSe2/graphene as compared to a more than fourfold enhancement for NbSe2 on insulating support substrates, and opens new prospects for using moiré engineering for controlling the collective states of 2D materials.
|
Dec 2025
|
|
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
I15-1-X-ray Pair Distribution Function (XPDF)
|
Daniel
Muñoz-Gil
,
Celia
Castillo-Blas
,
Dawid Krystian
Feler
,
Isabel
Gómez-Recio
,
Miguel
Tinoco
,
Ana
Querejeta-Fernández
,
Rodrigo
González-Prieto
,
Felipe
Gandara
,
Romualdo
Santos Silva
,
Pilar
Ferrer
,
Carlos
Prieto
,
Luc
Lajaunie
,
José Luis
Martinez-Peña
,
María Luisa
Ruiz-González
,
María Luisa
Ruiz-González
,
José María
González-Calbet
Diamond Proposal Number(s):
[40307, 40403]
Open Access
Abstract: Layered double hydroxides (LDH) based on transition metals are highly flexible in tailoring their dimensionality, lattice, and electronic structures, making them promising candidates as multifunctional 2D materials for the development of clean energy technologies and boosting the use of hydrogen as an energy vector. In this paper, strategic anion substitution in cobalt LDH is an appealing strategy to produce a material with two-fold functionality, electrochemical and magnetocaloric response, offering a sustainable alternative to existing electrocatalysts and cryogenic refrigerants. It is unambiguously demonstrated that (poly)oxomolybdate-based specimens interleave in Co LDH nanosheets up to a Co:Mo = 1:0.4 ratio, leading to an interstratified material. This intercalation greatly benefits the kinetics of the oxygen evolution reaction for H2 production, boosting the catalytic sites due to the expansion of the interlayer space, induced by the bulky molybdates which also partially modify the Co oxidation state of αCo(OH)2 nanolayers, favoring charge transfer. In parallel, the interleaved Mo species strengthen superexchange interactions compared with pristine α-Co(OH)2, effectively adjusting the operating temperature toward the liquid hydrogen range (2030 K). This specific temperature range allows to fill a critical gap in magnetocaloric materials, as few systems can simultaneously achieve both large magnetic entropy changes and structural stability.
|
Oct 2025
|
|
I05-ARPES
|
Qun
Wang
,
Yifang
Jiang
,
Songyuan
Geng
,
Hanpu
Liang
,
Yunbo
Wu
,
Risi
Guo
,
Fangjie
Chen
,
Kangjie
Li
,
Xin
Wang
,
Bin
Cao
,
Keyu
An
,
Shengtao
Cui
,
Zhe
Sun
,
Mao
Ye
,
Zhengtai
Liu
,
Changming
Yue
,
Shiming
Lei
,
Haoxiang
Li
Abstract: Engineering narrow-bandgap semiconductors remains a pivotal challenge for next-generation electronic and energy devices. Charge density wave (CDW) systems offer a promising platform for bandgap engineering. However, most 2D and 3D CDW systems remain metallic despite exhibiting Fermi surface nesting. Here, a doping-dependent metal-insulator transition (MIT) with tunable bandgaps is reported in square-net materials GdSbxTe2-x-δ and a cooperative interaction between CDWs and vacancies that drives the MIT is discovered. Angle-resolved photoemission spectroscopy (ARPES) reveals the MIT in the low Sb-content regime of GdSbxTe2-x-δ, with a maximum energy gap of Δ ≈ 98 meV at x = 0.16, corroborated by electrical transport measurements. Following the MIT, X-ray diffraction reveals a doping-dependent shift of the CDW wavevector toward a commensurate structure with q = 0.25 a*, concurrent with the appearance of Te vacancies in the square-net layers. Density functional theory (DFT) calculations attribute the gap formation to the ordered Te vacancies modulated by the 4×1×1 CDW superstructure, which suppresses the electronic states near the Fermi level. Contrasting with the partial gap scenarios in conventional CDW systems, this synergy between the CDW and the vacancy stabilizes the insulating phase, offering a distinct avenue for narrow bandgap engineering in electronic materials.
|
Oct 2025
|
|
|
|
Yafei
Chu
,
Chaocheng
Liu
,
Ruiqi
Liu
,
Weican
Lan
,
Lu
Cheng
,
Huijuan
Wang
,
Minghui
Fan
,
Hengli
Duan
,
Chao
Wang
,
Yajuan
Feng
,
Wensheng
Yan
Abstract: Twisted bilayer transition metal dichalcogenides (TMDs) have generated diverse unusual electrical and optical phenomena and can provide a powerful platform for designing nanodevices with tunable interlayer interaction. Striving to explore novel excitons with spin response in these semiconductor systems is highly desirable, as they highlight the possibility to access complex electronic band structure and magneto-exciton effect, thereby facilitating efficient spin-based information storage via exciton degrees of freedom. Here, fabrication of bilayer WSe2/Fe5GeTe2 (FGT) heterostructures with different stacking phases is reported, and a new hybridized excitonic state T* is defined in both 3R and 2H bilayer WSe2, which exhibits strong correlations dependent on the FGT spin order. This spin-dependent hybridized exciton is demonstrated to originate from the coupling between injected spin-polarized electrons and neutral excitons, because of the spin-cross-polarized band that obstructs the normal electron–hole annihilation process. Besides, the difference in the coupling strength of the T* exciton attributed to the distinct stacking symmetries in twisted bilayer WSe2 is further unveiled. These findings open an accessible avenue for designing tailored excitonic states in twisted bilayers, thus offering prospects for the future applications of stacking-engineered opto-spintronics at the integration level.
|
Oct 2025
|
|
E02-JEM ARM 300CF
|
Stefan
Heiserer
,
Natalie
Galfe
,
Michael
Loibl
,
Maximilian
Wagner
,
Oliver
Hartwig
,
Simon
Schlosser
,
Silke
Boche
,
William
Thornley
,
Nick
Clark
,
Kangho
Lee
,
Tanja
Stimpel‐lindner
,
Cormac
Ó Coileáin
,
Josef
Kiendl
,
Sarah J.
Haigh
,
George J.
De Coster
,
Georg S.
Duesberg
,
Paul
Seifert
Diamond Proposal Number(s):
[30728]
Open Access
Abstract: 2D layered materials such as PtSe2 are prime candidates for next-generation micro- and nano-electro–mechanical systems (MEMS/NEMS), including piezoresistive sensors. However, due to difficulties in large-scale synthesis and the inherent drawbacks associated with mechanical transfer of 2D material films, scalable NEMS production remains challenging. In this work, we report a fabrication route for free-standing, as-grown 2D material channels of PtSe2 with controlled dimensions, avoiding a mechanical film transfer. The free-standing devices provide a universal platform for strain engineering of 2D materials because tension can be easily controlled by application of a back-contact voltage. Moreover, the piezoresistivity of PtSe2, together with the possibility of wafer-scale synthesis at back-end-of-line compatible growth temperatures, make it ideally suited for scalable incorporation into integrated circuits. Our measurements show that the material properties can be tuned via strain, which offers pathways for classically non-gateable materials in electronic and photonic devices. Finite element simulations of representative free-standing films elucidate the nano–mechanical properties of large-scale-grown, polycrystalline 2D materials under tensile strain and demonstrate the influence of polycrystallinity on the optical and electrical behavior.
|
Aug 2025
|
|
