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Combining machine learning algorithms with traditional methods for resolving the atomic-scale dynamic structure of monolayer MoS_(2) in high-resolution transmission electron microscopy

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Chinese physics B 2025年第1期34卷 162-170页

作者： Yu Meng Shuya Wang Xibiao Ren Han Xue Xuejun Yue Chuanhong Jin Shanggang Lin Fang Lin Department of Applied Physics College of Electronic EngineeringSouth China Agricultural UniversityGuangzhou 510642China State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

High-resolution transmission electron microscopy(HRTEM)promises rapid atomic-scale dynamic structure ***,the precision limitations of aberration parameters and the challenge of eliminating aberrations in Cs-corrected transmission electron microscopy constrain resolution.A machine learning algorithm is developed to determine the aberration parameters with higher precision from small,lattice-periodic crystal *** proposed algorithm is then validated with simulated HRTEM images of graphene and applied to the experimental images of a molybdenum disulfide(MoS_(2))monolayer with 25 variables(14 aberrations)resolved in wide *** these measured parameters,the phases of the exit-wave functions are reconstructed for each image in a focal series of MoS_(2)*** images were acquired due to the unexpected movement of the specimen ***-dimensional data extraction reveals time-varying atomic structures and *** particular,the atomic evolution of the sulfur-vacancy point and line defects,as well as the edge structure near the amorphous,is visualized as the resolution has been improved from about 1.75?to 0.9 *** method can help salvage important transmission electron microscope images and is beneficial for the images obtained from electron microscopes with average stability.

关键词： aberration measurement high-resolution transmission electron microscopy feature-extraction networks exit-wave reconstruction monolayer MoS_(2)

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First principles calculations of Sb2Se3 and SCAPS-1D simulation-guided optimization for improved photovoltaic properties in solar cells

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Optical and Quantum Electronics 2025年第3期57卷 1-26页

作者： Ullah, Javid Rehman, Zia Ur Anum, Khadija ahmad, Ibrar Ali, Tahir Hayat, Khizar Shah, Said Karim Department of Physics Abdul Wali Khan University Mardan Khyber Pakhtunkhwa Mardan23200 Pakistan Department of Basic and Applied Sciences for Engineering Sapienza University of Rome Rome00185 Italy Physics Division PINETECH Nilore Islamabad44000 Pakistan

This study explores the potential of Antimony Selenide (Sb₂Se₃) as an absorber layer (AL) for solar cells (SCs), focusing on its optical and electronic properties for enhancing photovoltaic performance. Using SCAPS-1D simulation and density functional theory (DFT), the material’s indirect bandgap of 1.12 eV was confirmed, with photon absorption beginning above 1 eV. The reflectivity of Sb₂Se₃ is significant in the 2.5–12 eV range, and its energy loss function is minimal in the visible spectrum, which is critical for achieving high-efficiency solar cells. Additionally, the optical conductivity peaks between 2 and 12 eV, with a maximum extinction coefficient at 2 and 9 eV, further highlighting its suitability for solar applications. The study optimizes device parameters, including defect density (Nt), absorber layer thickness, acceptor (NA) and donor (ND) densities, and series (Rs) and shunt (Rsh) resistances. The impact of environmental factors such as working temperature (WT) and sunlight intensity on device performance was also systematically investigated to understand the efficiency of Sb₂Se₃ solar cells under real-world conditions. Copper thiocyanate (CuSCN) and tin sulphate (SnS₂) were identified as the optimal electron transfer layer (ETL) and hole transfer layer (HTL), respectively. After these optimizations, the device demonstrated a remarkable power conversion efficiency (PCE) of 28.38%, with a short-circuit current density (Jsc) of 40.32 mA/cm2, an open-circuit voltage (Voc) of 0.8207 V, and a fill factor (FF) of 85.78%. These results underscore the promising potential of Sb₂Se₃ as a high-efficiency absorber material for solar cells, with significant implications for future photovoltaic device development and material optimization strategies. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

关键词： Optical conductivity

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Thermopressure Coupling Effect Mimicking Natural Graphite Formation to Enhance the Storage K-Ion Performance of Carbonaceous Heterostructures

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Research 2023年第4期2023卷 379-389页

作者： Tianyi Ji Xiaoxu Liu Hui Wang Yunli Shi Yang Li Man Zhang Junqi Li Hui Liu Ze Xiang Shen Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials School of Material Science and EngineeringShaanxi University of Science and TechnologyXi’an 710021ShaanxiChina Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore

Borrowing from natural mechanisms for material design can lead to functional mimicry and *** by graphite formation,a thermopressure coupling strategy under micropressure(<400 Pa)is applied to prepare carbon anodes.A thermopressure response is discovered based on the cellulose ***,homologous graphene quantum dot/hard carbon(GQD/HC)heterostructures are *** 181.4 Pa and 1,200°C,the product shows a capacity of 310 mAh g^(−1),while the capacity of the direct carbonization product is only 120 mAh g^(−1).Prominently,the GQD/HC heterostructure displays marked mechanical strength and *** experimental and theoretical results illustrate the ion and electron transfer,coordination environment,and electronic states in the GQD/HC heterostructure and elaborate on the origin of the enhanced *** thermopressure coupling under micropressure mimics graphite formation,but the heterostructure has better properties than traditional carbon ***,micropressure injects new vitality into material research.

关键词： coupling Coupling Carbon

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Observation of an acoustic non-Hermitian topological Anderson insulator

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Science China(physics,Mechanics & Astronomy) 2023年第9期66卷 57-62页

作者： Zhongming Gu He Gao Haoran Xue Di Wang Jiamin Guo Zhongqing Su Baile Zhang Jie Zhu Institute of Acoustics School of Physics Science and EngineeringTongji UniversityShanghai 200092China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore Centre for Disruptive Photonic Technologies Nanyang Technological UniversitySingapore 637371Singapore

The interaction of band topology and disorder can give rise to intriguing *** paradigmatic example is the topological Anderson insulator,whose nontrivial topology is induced in a trivial system by *** this study,we investigate the efect of purely non-Hermitian disorders on topological systems using a one-dimensional acoustic lattice with coupled ***,we construct a theoretical framework to describe the non-Hermitian topological Anderson insulator phase solely driven by disordered loss ***,the complete evolution of non-Hermitian disorder-induced topological phase transitions,from an initial trivial phase to a topological Anderson phase and finally to a trivial Anderson phase,is revealed experimentally using both bulk and edge ***,topological modes induced by non-Hermitian disorders to be immune to both weak Hermitian and non-Hermitian *** findings pave the way for future research on disordered non-Hermitian systems for novel wave manipulation.

关键词： topological Anderson insulator non-Hermitian systems topological edge states

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A metamaterial-free fluid-flow cloak

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National Science Review 2022年第9期9卷 212-218页

作者： Fuyang Tay Youming Zhang Hongyi Xu Honghui Goh Yu Luo Baile Zhang Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University School of Electrical and Electronic Engineering Nanyang Technological University Centre for Disruptive Photonic Technologies Nanyang Technological University

The model of ide al fluid flow around a cylindrical obstacle exhibits a long-established physical picture,where originally straight streamlines are deflected over the whole space by the *** by transformation optics and metamaterials,recent theories have proposed the concept of fluid cloaking,which is able to recover the straight streamlines,as if the obstacle did not ***,such a cloak,similar to all previous transformation-optics-based devices,relies on complex metamaterials with inhomogeneous parameters and is difficult to *** we deploy the theory of scattering cancellation and report on the experimental realization of a fluid-flow cloak without *** clo ak is realized by engineering the geometry of the fluid channel,which effectively cancels the dipole-like scattering of the *** clo aking effect is demonstrated through the direct observation of recovered straight streamlines in the fluid *** work sheds new light on conventional fluid control and may find application in microfluidic devices.

关键词： invisibility cloaks metamaterials fluid-flow control

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Deep learning approaches for instantaneous laser absorptance prediction in additive manufacturing

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npj Computational Materials 2024年第1期10卷 3210-3222页

作者： Runbo Jiang John Smith Yu-Tsen Yi Tao Sun Brian J.Simonds Anthony D.Rollett Department of Materials Science and Engineering Carnegie Mellon UniversityPittsburghPA 15213USA Department of Materials Science and Engineering University of VirginiaCharlottesvilleVA 22904USA Applied Physics Division National Institute of Standards and TechnologyBoulderCO 80305USA NextManufacturing Center Carnegie Mellon UniversityPittsburghPA 15213USA

The quantification of absorbed light is essential for understanding laser-material interactions and melt pool dynamics in order to minimize defects in additively manufactured metal *** geometry of a vapor depression formed during laser melting is closely related to laser energy *** relationship has been observed by the state-of-the-art in situ high-speed synchrotron X-ray visualization and integrating sphere *** two techniques create a temporally resolved dataset consisting of vapor depression images and corresponding laser *** this work,we propose two different approaches to predict instantaneous laser *** end-to-end approach uses deep convolutional neural networks to learn implicit features of X-ray images automatically and predict the laser energy *** two-stage approach uses a semantic segmentation model to engineer geometric features and predict absorptance using classical regression *** having distinct advantages,both approaches achieved a consistently low mean absolute error of less than 3.3%.

关键词： additive prediction Deep

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High-excited-state splitting and multimode vibrational coupling in Mn^(4+)-activated fluoride phosphor

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Science China(physics,Mechanics & Astronomy) 2024年第3期67卷 95-101页

作者： Debao Zhang Wanggui Ye Xuguang Cao Ji Zhou Fei Tang Changcheng Zheng Jiqiang Ning Shijie Xu Department of Optical Science and Engineering School of Information Science and TechnologyFudan University Shanghai 200438China Jiangsu Key Laboratory of Advanced Laser Materials and Devices Schoolof Physics and Electronic Engineering Jiangsu Normal UniversityXuzhou 221116China Division of Natural and Applied Sciences Duke Kunshan UniversityKunshan 215316China

Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn^(4+)ions in K_(2)SiF_(6) microcrystals via measuring and calculating their variable-temperature photoluminescence excitation(PLE) spectra. At cryogenic temperatures, an unpredicted splitting of the high-excited-state is observed. Moreover, the two-split high-excited-state levels are further revealed to primarily couple with the two hyperfine split modes of quasi-localized ν2 vibration in the distorted Mn-F_(6) octahedral configuration,whereas the coupling strengths are found to be substantially different from each other. The slightly split vibrational mode is firmly supported by the low-temperature Raman spectra. Jahn-Teller lattice distortion is believed to be responsible for the observed splitting of the electronic high-excited-state and the quasi-localized vibrational mode.

关键词： splitting of excited-state photoluminescence excitation spectrum electron-phonon coupling Jahn-Teller effect

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Exotic Spin Excitations in a Polar Magnet VOSe2O5

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Physical Review Letters 2024年第13期133卷 136702页

作者： Tomonao Araki Rina Takagi Takashi Kurumaji Yoshinori Tokura Masahito Mochizuki Shinichiro Seki Department of Applied Physics and Institute of Engineering Innovation PRESTO Division of Physics Mathematics and Astronomy Wako 351-0198 Japan Tokyo College Department of Applied Physics

Magnetic resonance dynamics has been studied for a polar magnet VOSe2O5, which hosts several nontrivial magnetic phases including Néel-type skyrmion lattice (SkL). In both cycloidal and SkL spin states, two excitation modes active to oscillating magnetic field Bν⊥c and one mode active to Bν∥c are identified. The subsequent micromagnetic simulations well reproduce the observed selection rules and relative resonance frequencies, which allows the unambiguous assignment of the spin oscillation manner for each mode. Interestingly, the IC-2 phase with a potential double-q character was found to host similar excitation modes as the SkL state. We also discovered the existence of the novel B’ phase with four modes active to Bν⊥c. The present results provide a fundamental basis for the comprehensive understanding of resonant spin dynamics in polar magnets, and highlight VOSe2O5 as a unique material platform to host a rich variety of nontrivial spin excitations.

关键词： Magnetic texture Spin dynamics Noncollinear magnets Single crystal materials Electron spin resonance Landau-Lifschitz-Gilbert equation Monte Carlo methods

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Thin film chalcogenides and optical design for mid-infrared sensing applications

Thin film chalcogenides and optical design for mid-infrared ...

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CLEO: Science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： El-Kholy, Ibrahim Al-Alexis Khan, Amir Division of Physics Engineering Mathematics and Computer Science Optical Science Center for Applied Research Delaware State University DoverDE United States

ISBN: (纸本)9781957171395

Constituent elements of Ge-Se-S glasses were chosen with different compositions such as Ge2Se8, Ge2S8, Se2S8, and GeSe2S2 to study their optical properties for UV, visible, and Mid-IR range using different optical tools like UV-Vis, FTIR, and Raman spectroscopy for mid-infrared thin film applications. © Optica Publishing Group 2024

关键词： Fourier transform infrared spectroscopy

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Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal

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National Science Review 2024年第11期11卷 47-53页

作者： Peiheng Zhou Gui-Geng Liu Zihao Wang Shuwei Li Qindong Xie Yunpeng Zhang Subhaskar Mandal Xiang Xi Zhen Gao Longjiang Deng Baile Zhang National Engineering Research Center of Electromagnetic Radiation Control Materials Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of EducationUniversity of Electronic Science and Technology of China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University School of Electrical Engineering and Intelligentization Dongguan University of Technology Department of Electronic and Electrical Engineering Southern University of Science and Technology Centre for Disruptive Photonic Technologies The Photonics InstituteNanyang Technological University

The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal(Ph C) with broken time-reversal symmetry(T), hosting chiral edge states that are topologically protected propagating modes. Along a separate line of research, a quadrupole topological insulator was the first higher-order topological phase supporting localized corner states, but has been so far limited to T-invariant systems, as T is a key ingredient in early models. Here we report the realization of a quadrupole topological insulator phase in a gyromagnetic Ph C, as a consequence of topological phase transition from the previously demonstrated Chern insulator phase. The phase transition has been demonstrated with microwave measurements, which characterize the evolution from propagating chiral edge states to localized corner states. We also demonstrate the migration of topological boundary states into the continuum, when the gyromagnetic Ph C is magnetically tuned. These results extend the quadrupole topological insulator phase into T-broken systems, and integrate topologically protected propagating and localized modes in a magnetically tunable photonic crystal platform.

关键词： quadrupole topological insulator time-reversal symmetry breaking corner states topological phase transition

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