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SSRN 2023年

作者： Sun, Wenjun Wu, Xiangmin Cheng, Yongjun Dong, Meng Ma, Zhuoya Jia, Wenjie Zhang, Yafei Zhang, Ruifang Wu, Chengyao Feng, Cun Luo, Honggang School of Physical Science and Technology Lanzhou University Lanzhou730000 China Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of Physics Lanzhou730000 China

Accurate measurements in ultrahigh vacuum (UHV) are increasingly critical for scientific research and industrial applications. Here, we report an experimental study of UHV measurements performed on a 7Li cold atom vacuum measurement setup. The setup enables cold atom vacuum measurements in the magneto-optical and magnetic traps (CAVM-MOT and CAVM-MT), respectively. The precision of the vacuum measurements in both traps was effectively improved after optimisation of the excited-state fraction data processing for CAVM-MOT and the initial loading control method for CAVM-MT. A comparison of the measurement methods was carried out in combination with an ionisation gauge, revealing the good linearity and accuracy of the CAVM. We believe that CAVM in the two potential traps have their own application situations and development directions, respectively. © 2023, The Authors. All rights reserved.

关键词： Excited states

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Obstructed atomic insulators with robust corner modes

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Physical Review B 2023年第10期108卷 L100101-L100101页

作者： Da-Shuai Ma Kejun Yu Xiao-Ping Li Xiaoyuan Zhou Rui Wang Institute for Structure and Function & Department of Physics & Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing 400044 People's Republic of China Center of Quantum materials and devices Chongqing University Chongqing 400044 People's Republic of China Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China

Higher-order topological insulators (HOTIs), that are classified as obstructed atomic insulators (OAIs) in the topological quantum chemistry (TQC) theory, attract great interest owning to the lower-dimensional topological boundary states. However, the boundary states in HOTIs reported so far are often fragile, manifested as strongly depending on crystalline symmetries and cleavage terminations in the disk or cylinder geometry. Here, using the TQC theory, we propose an intuitive strategy to establish the connection between the obstructed Wannier charge centers of OAIs and the emergence of robust corner states in two-dimensional systems. Based on first-principles calculations and real space invariant theory, we extend the concept of OAIs to phonon systems and thereby predict that the robust corner states can be realized in the phonon spectra of MX3 (M = Bi, Sb, As, Sc, Y; X = I, Br, Cl) monolayers. The phonon corner modes in different shapes of nanodisks are investigated, and their robustness facilitates the detection in experiments and further applications. This work suggests a promising avenue to explore more attractive features of higher-order band topology beyond the existing paradigm.

关键词： Edge states First-principles calculations Phonons Topological materials Topological phases of matter 2-dimensional systems Topological insulators High-throughput calculations Wannier function methods

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The Progress in Optimization of Small-scale Calibration Targets at THz Frequencies 4

The Progress in Optimization of Small-scale Calibration Targ...

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4th International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2021

作者： Yuan, Ruili Li, Xiang Gao, Qingsong Tao, Yuan Jin, Ming College of Information Science and Technology Beijing University of Chemical Technology Beijing China Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of Physics Lanzhou China

ISBN: (纸本)9781733509619

In this paper, the small-sized blackbody (calibration targets) is optimized for better wide-band low-reflectivity performance. The pyramidal unit is optimized with a curved kernel, also with the nonuniform coating layer. The reflectivity performance of the coated pyramids is investigated from 50GHz to 700GHz, based on the full-wave finite difference time domain (FDTD) computations. Comparing to the original uniformly coated pyramid, the optimized design achieves better absorption in the low-frequency region, and eliminates Fabre-Perot(F-P) resonance which leads to frequency ripples at high frequencies. In addition, different structural parameters of the pyramidal unit are investigated, such as periods and height/period ratios. This work provides a reference for the further optimization of the calibration target in the future. © 2021 Applied Computational Electromagnetics Society (ACES).

关键词： Reflection

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Observation of multiple surface states in naturally cleavable chiral crystal PdSbSe

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Physical Review Materials 2025年第3期9卷 L031201-L031201页

作者： Zhicheng Jiang Zhengtai Liu Chenqiang Hua Xiangqi Liu Yichen Yang Jianyang Ding Jiayu Liu Jishan Liu Mao Ye Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201210 China National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology University of Science and Technology of China Hefei 230026 China National Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information Technology (SIMIT) Chinese Academy of Sciences Shanghai 200050 China Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou 310027 China State Key Lab of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Beihang Hangzhou Innovation Institute Yuhang Xixi Octagon City Yuhang District Hangzhou 310023 China School of Physical Science and Technology ShanghaiTech University Shanghai 200031 China State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

Chiral multifold fermions in solids exhibit unique band structures and topological properties, making them ideal for exploring fundamental physical phenomena related to nontrivial topology, chirality, and symmetry breaking. However, the challenge of obtaining clean, flat surfaces through cleavage has hindered the investigation of their unique electronic states. In this study, we utilize high-resolution angle-resolved photoemission spectroscopy and density functional theory calculations to investigate the low-energy electronic structure of the cleavable single-crystal PdSbSe. Our combined experimental and theoretical analysis reveals the presence of multifold-degenerate fermions within this chiral crystal. We also observe multiple chiral Fermi arc surface states and spin-splitting behavior in the associated bulk bands. These findings provide unique insights into chiral, multifold fermionic states in easily cleavable crystals and offer a robust platform for further research into their unique electronic properties and potential applications in novel electronic devices.

关键词： Photoelectron spectroscopy

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Simultaneously removal of P and B from Si by Sr and Zr co-addition during Al–Si low-temperature solvent refining

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International Journal of Minerals,Metallurgy and Materials 2023年第2期30卷 365-377页

作者： Chen Chen Jingwei Li Qiuxia Zuo Boyuan Ban Jian Chen Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China State Key Laboratory of Mineral Processing BGRIMM Technology GroupBeijing 100160China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650504China Engineering Research Center of High Performance Copper Alloy Materials and Processing Ministry of EducationHefei University of TechnologyHefei 230009China Shandong Aluminum Vocational College Weihai 264400China

To remove the key impurity elements,P and B,from primary Si simultaneously,Sr and Zr co-addition to Al-Si alloy systems during solvent refining has been *** reacts with Al,Si,and P in the melt to form a P-containing Al_(2)Si_(2)Sr phase and Zr reacts with B to form a ZrB_(2) *** the Al-Si-Sr-Zr system,high removal fractions of P and B in the primary Si,with 84.8%-98.4%and 90.7%-96.7%,respectively,are achieved at the same time,*** best removal effect is obtained in the sample with the addition of Sr-32000+Zr-3000μg·kg^(-1),and the removal fractions of P and B in the purified Si reach 98.4%and 96.1%.Compared with the Sr/Zr single-addition,the removal effects of Sr and Zr co-addition on P and B do not show a significant downward trend,indicating that the nucleation and growth of the B/P-containing impurity phases are mutually ***,an evolution model is proposed to describe the nucleation and the growth stages of Sr/Zr-containing compound phases,which reveals the interaction between the impurity phases and the primary Si.

关键词： Al2Si2Sr phase zirconium boride phase phase directional solidification solvent refining

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Near-Field Radiative Heat Transfer between Disordered Multilayer Systems

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Chinese physics Letters 2023年第6期40卷 92-97页

作者：田鹏葛文宣李松松高雷蒋建华徐亚东 Institute of Theoretical and Applied Physics School of Physical Science and TechnologySoochow UniversitySuzhou 215006China Department of Photoelectric Science and Energy Engineering Suzhou City UniversitySuzhou 215104China Key Lab of Modern Optical Technologies of Ministry of Education Soochow UniversitySuzhou 215006China

Near-field radiative heat transfer(NFRHT) research is an important research project after a major breakthrough in nanotechnology. Based on the multilayer structure, we find that due to the existence of inherent losses,the decoupling of hyperbolic modes(HMs) after changing the filling ratio leads to suppression of heat flow near the surface mode resonance frequency. It complements the physical landscape of enhancement of near-field radiative heat transfer by HMs and more surface states supported by multiple surfaces. More importantly, considering the difficulty of accurate preparation at the nanoscale, we introduce the disorder factor to describe the magnitude of the random variation of the layer thickness of the multilayer structure and then explore the effect on heat transfer when the layer thickness is slightly different from the exact value expected. We find that the near-field radiative heat flux decreases gradually as the disorder increases because of interlayer energy localization. However, the reduction in heat transfer does not exceed an order of magnitude, although the disorder is already very large. At the same time, the regulation effect of the disorder on NFRHT is close to that of the same degree of filling ratio,which highlights the importance of disordered systems. This work qualitatively describes the effect of disorder on heat transfer and provides instructive data for the fabrication of NFRHT devices.

关键词： radiative multilayer instru

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Influence of High-Pressure Induced Lattice Dislocations and Distortions on Thermoelectric Performance of Pristine SnTe

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Chinese physics Letters 2024年第5期41卷 61-68页

作者：郑博文陈涛孙海瑞杨曼曼杨兵超陈欣张永胜刘晓兵 Laboratory of High-Pressure Physics and Materials Science School of Physics and Physical EngineeringQufu Normal UniversityQufu 273165China Advanced Research Institute of Multidisciplinary Sciences Qufu Normal UniversityQufu 273165China Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State Physics HFIPSChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China School of Electronic Engineering Huainan Normal University Huainan 232038China

As a sister compound of PbTe, SnTe possesses the environmentally friendly elements. However, the pristine SnTe compounds suffer from the high carrier concentration, the large valence band offset between the L and Σpositions and high thermal conductivity. Using high-pressure and high-temperature technology, we synthesized the pristine SnTe samples at different pressures and systemically investigated their thermoelectric *** pressure induces rich microstructures, including the high-density dislocations and lattice distortions, which serve as the strong phonon scattering centers, thereby reducing the lattice thermal conductivity. For the electrical properties, pressure reduces the harmful high carrier concentration, due to the depression of Sn ***, pressure induces the valence band convergence, reducing the energy separation between the L and Σpositions. The band convergence and suppressed carrier concentration increase the Seebeck coefficient. Thus, the power factors of pressure-sintered compounds do not deteriorate significantly under the condition of decreasing electrical conductivity. Ultimately, for a pristine SnTe compound synthesized at 5 GPa, a higher ZT value of 0.51 is achieved at 750 K, representing a 140% improvement compared to the value of 0.21 obtained using SPS. Therefore, the high-pressure and high-temperature technology is demonstrated as an effectively approach to optimize thermoelectric performance.

关键词： coefficient properties positions

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Anomalous Nernst Effect Induced Terahertz Emission in a Single Ferromagnetic Film

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Nano Letters 2023年第17期23卷 8171-8179页

作者： Feng, Zheng Tan, Wei Jin, Zuanming Chen, Yi-Jia Zhong, Zhangfeng Zhang, Liang Sun, Song Tang, Jin Jiang, Yexing Wu, Po-Hsun Cheng, Jun Miao, Bingfeng Ding, Haifeng Wang, Dacheng Zhu, Yiming Guo, Liang Shin, Sunmi Ma, Guo-Hong Hou, Dazhi Huang, Ssu-Yen Microsystem & Terahertz Research Center CAEP Chengdu610200 China Terahertz Technology Innovation Research Institute Terahertz Spectrum and Imaging Technology Cooperative Innovation Center Shanghai Key Lab of Modern Optical System University of Shanghai for Science and Technology Shanghai200093 China Department of Physics National Taiwan University Taipei10617 Taiwan National Laboratory of Solid State Microstructures and Department of Physics Nanjing University Nanjing210093 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Physics and Optoelectronics Engineering Science Anhui University Hefei230601 China Department of Mechanical Engineering National University of Singapore 117516 Singapore Department of Physics Shanghai University Shanghai200444 China ICQD Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei230026 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Department of Physics University of Science and Technology of China Hefei230026 China

Despite its important role in understanding ultrafast spin dynamics and revealing novel spin/orbit effects, the mechanism of the terahertz (THz) emission from a single ferromagnetic nanofilm upon a femtosecond laser pump still remains elusive. Recent experiments have shown exotic symmetry, which is not expected from the routinely adopted mechanism of ultrafast demagnetization. Here, by developing a bidirectional pump-THz emission spectroscopy and associated symmetry analysis method, we set a benchmark for the experimental distinction of the THz emission induced by various mechanisms. Our results unambiguously unveil a new mechanism─anomalous Nernst effect (ANE) induced THz emission due to the ultrafast temperature gradient created by a femtosecond laser. Quantitative analysis shows that the THz emission exhibits interesting thickness dependence where different mechanisms dominate at different thickness ranges. Our work not only clarifies the origin of the ferromagnetic-based THz emission but also offers a fertile platform for investigating the ultrafast optomagnetism and THz spintronics. © 2023 American Chemical Society.

关键词： Emission spectroscopy

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Surface repair of wide-bandgap perovskites for high-performance all-perovskite tandem solar cells

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Journal of Energy Chemistry 2024年第6期93卷 64-70,I0003页

作者： Xiaojing Lv Weisheng Li Jin Zhang Yujie Yang Xuefei Jia Yitong Ji Qianqian Lin Wenchao Huang Tongle Bu Zhiwei Ren Canglang Yao Fuzhi Huang Yi-Bing Cheng Jinhui Tong State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070HubeiChina Key Lab of Artificial Micro-and Nano-Structures of Ministry of Education of China School of Physics and TechnologyWuhan UniversityWuhan 430072HubeiChina Department of Electrical and Electronic Engineering Photonics Research Institute(PRI)Research Institute for Intelligent Wearable Systems(iWEAR)The Hong Kong Polytechnic University999077Hong KongChina Laboratory of Advanced Materials Fudan UniversityShanghai 200438China Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Foshan 528200GuangdongChina

Wide-bandgap(WBG)perovskite solar cells(PSCs)play a fundamental role in perovskite-based tandem solar ***,the efficiency of WBG PSCs is limited by significant open-circuit voltage losses,which are primarily caused by surface *** this study,we present a novel method for modifying surfaces using the multifunctional S-ethylisothiourea hydrobromide(SEBr),which can passivate both Pb^(-1)and FA^(-1)terminated surfaces,Moreover,the SEBr upshifted the Fermi level at the perovskite interface,thereby promoting carrier *** proposed method was effective for both 1.67 and 1.77 eV WBG PSCs,achieving power conversion efficiencies(PCEs)of 22.47%and 19.90%,respectively,with V_(OC)values of 1.28 and 1.33 V,along with improved film and device *** this advancement,we were able to fabricate monolithic all-perovskite tandem solar cells with a champion PCE of 27.10%,This research offers valuable insights for passivating the surface trap states of WBG perovskite through rational multifunctional molecular engineering.

关键词： Wide-bandgap perovskite Surface defect Multifunctional molecule All-perovskite tandem solar cells

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Pressure-driven metallization with significant changes of structural and photoelectric properties in two-dimensional EuSbTe_(3)

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Rare Metals 2024年第11期43卷 5943-5952页

作者： Zhi-Kai Zhu Zhong-Yang Li Zhen Qin Yi-Ming Wang Dong Wang Xiao-Hui Zeng Fu-Yang Liu Hong-Liang Dong Qing-Yang Hu Ling-Ping Kong Hao-Zhe Liu Wen-Ge Yang Yan-Feng Guo Shuai Yan Xuan Fang Wei He Gang Liu State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materialsand School of ResourcesEnvironment and MaterialsGuangxi UniversityNanning 530004China Center for High Pressure Science and Technology Advanced Research(HPSTAR) Shanghai 201203China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Poly Technologies INCBeijing 100010China ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China Sch Sci State Key Lab High Power Semicond LasersChangchun University Science and TechnologyChangchun 130022China Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments(MFree) Shanghai Advanced Research in Physical Sciences(SHARPS)Shanghai 201203China

Two-dimensional materials are widely considered to be highly promising for the development of *** improve the performance of these devices,researchers often employ techniques such as defect ***,pressure is employed as a clean and novel means to manipulate the structural and physical properties of EuSbTe_(3),an emerging two-dimensional *** experimental results demonstrate that the structural phase transformation of EuSbTe_(3)occurs under pressure,with an increase in infrared reflectivity,a band gap closure,and a metallization at *** with X-ray diffraction(XRD)and Raman characterizations,it is evident that the pressure-driven transition from semiconductor Pmmn phase to metallic Cmcm phase causes the disappearance of the charge density ***,at a mild pressure,approximately 2 GPa,the maximum photocurrent of EuSbTe_(3)is three times higher than that at ambient condition,suggesting an untapped potential for various practical applications.

关键词： Pressure Phase transition Metallization Photoresponse Two-dimensional(2D)

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