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GRB 21.61.B:The Internal and External Plateau as Evidence for the Delayed Outflow of Magnetar

Research in Astronomy and astrophysics 2024年第7期24卷 170-180页

作者： Yi-Ning Wei Xiang-Gao Wang Da-Bin Lin Wei-Kang Zheng Liang-Jun Chen Sheng-Yu Yan Shuang-Xi Yi Qi Wang Zi-Min Zhou Hui-Ya Liu En-Wei Liang Guangxi Key Laboratory for Relativistic astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China GXU-NAOC center for {1. and Space Sciences Nanning 530004China department of Astronomy University of CaliforniaBerkeleyCA 94720-3411USA department of {1. and tsinghua center for astrophysics(THCA) Tsinghua UniversityBeijing 100084China School of physics and Physical Engineering Qufu Normal UniversityQufu 273165China

After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission together with the energy injection feature in a single observation poses confusion until the long gamma-ray burst(GRB)21.61.B is *** 21.61.B is presented with an optical bump following an early X-ray plateau during the afterglow *** plateau followed by a steep decline flux overlays in the steadily decaying X-ray flux with indexα_(X,1.~2.06,indicating an internal origin and that can be fitted by the spin-down luminosity law with the initial plateau luminosity log_(1.)L_(X)~48.29 erg s~(-1.and the characteristic spin-down timescale T~281. s.A subsequent bump begins at~4000 s in the R band with a rising indexα_(R,1.~-0.30 and peaks at~1.1.5 s,after which a decay indexα_(R,2)~0.87 and finally transiting to a steep decay withα_(R,3)~1.77 achieve the closure relation of the external shock for the normal decay phase as well as the magnetar spin-down energy injection phase,provided that the average value of the photon indexΓ_γ=1.80 derived from the spectral energy distributions(SEDs)between the X-ray and optical *** closure relation also works for the late X-ray *** to the traditional picture of GRB,the outflow powers the early X-ray plateau by dissipating energy internally and collides with the leading decelerating blast burst as time goes on,which could interpret the exotic feature of GRB *** carry out a Markov Chain Monte Carlo simulation and obtain a set of best parameters:■.The artificial light curve can fit the afterglow data *** that,we estimated the average Lorentz factor and the X-ray radiation efficiency of the later ejecta are 35%and 0.1.%,respectively.

关键词： (stars)gamma-ray burst individual(GRB 21.61.B)-(stars)gamma-ray burst general-stars jets

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Influences of chemical reactions on polysulfide reduction reaction process on promotor surface in Li-S batteries

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Nano Research 2024年第4期17卷 2712-2718页

作者： Yufeng Luo Zhenhan Fang Zixin Hong Shaorong Duan Haitao Liu Hengcai Wu Qunqing Li Yuegang Zhang Shoushan Fan Wenhui Duan Jiaping Wang tsinghua-Foxconn Nanotechnology Research {1. Tsinghua UniversityBeijing 100084China department of {1. Tsinghua UniversityBeijing 100084China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Frontier Science center for Quantum Information Tsinghua UniversityBeijing 100084China

Polar promotors have been proven effective in catalyzing the polysulfide(PS)reduction reaction(PSRR)process in lithium-sulfur(Li-S)***,the promotor surface tends to be poisoned due to the accumulation of insoluble discharging products of lithium disulfide(Li_(2)S_(2))and lithium sulfide(Li_(2)S)during Li-S battery ***,we investigate the detailed PSRR mechanism on the surface of manganese sulfides(MnS)as a representative promoter by performing in-situ Raman mapping *** catalytic ability of MnS enables thorough electrochemical reduction of PSs to Li_(2)S_(2) and Li_(2)S on the MnS *** generated Li_(2)S_(2) and Li_(2)S then adsorb the dissolved PSs via chemical reactions among sulfur species during the subsequent PSRR *** phenomenon mitigates promotor poisoning and continuously improves the reversible ***,the assembled Li-S cell demonstrates excellent electrochemical performance after introducing a conductive interlayer containing a thin piece of carbon nanotube film and MnS promotors.

关键词： promotors polysulfides chemical reactions catalytic ability in-situ Raman measurements

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Measurement of the high energyγ-rays from heavy ion reactions usingČerenkov detector

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Nuclear Science and Techniques 2024年第2期35卷 123-130页

作者： Da-Wei Si Yan Zhou Sheng Xiao Zhi Qin Dong Guo Yu-Hao Qin Yi-Jie Wang Bo-Yuan Zhang Bai-Ting Tian Zhi-Gang Xiao department of {1. Tsinghua UniversityBeijing 100084China

The energetic bremsstrahlung photons up to 1.0 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51.2)∕E^(1.2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1.2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×1.0 cm, respectively, to detect high-energy γ-rays at 1.0 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.

关键词： Bremsstrahlungγ-rays Čerenkov Geant4 Energy resolution Direction reconstruction Hough transform

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Proposal for a realtime Einstein-synchronization-defined satellite virtual clock

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Chinese physics B 2024年第7期33卷 268-276页

作者：严晨皓汤雪逸王时光孟李皎悦孙海媛何奕彬王力军 department of Precision Instrument Tsinghua UniversityBeijing 100091China department of {1. Tsinghua UniversityBeijing 100091China

Realization of high performance satellite onboard clock is vital for various positioning, navigation, and timing applications. For further improvement of the synchronization-based satellite time and frequency references, we propose a geosynchronous(GEO) satellite virtual clock concept based on ground–satellite synchronization and present a beacon transponder structure for its implementation(scheduled for launch in 2025), which does not require atomic clocks to be mounted on the satellite. Its high performance relies only on minor modifications to the existing transponder structure of GEO satellites. We carefully model the carrier phase link and analyze the factors causing link asymmetry within the special relativity. Considering that performance of such synchronization-based satellite clocks is primarily limited by the link's random phase noise, which cannot be adequately modeled, we design a closed-loop experiment based on commercial GEO satellites for pre-evaluation. This experiment aims at extracting the zero-means random part of the ground-satellite Ku-band carrier phase via a feedback loop. Ultimately, we obtain a 1. value of 0.633 ps(two-way link), following the Gaussian distribution. From this result, we conclude that the proposed real-time Einstein-synchronization-defined satellite virtual clock can achieve picosecond-level replication of onboard time and frequency.

关键词： Einstein synchronization satellite virtual clock geosynchronous satellite carrier phase

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Tailoring Electrode–Electrolyte Interface Using an Electron-Deficient Borate-Based Additive in MgTFSI_(2)-MgCl_(2)/DME Electrolyte for Rechargeable Magnesium Batteries

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Energy & Environmental Materials 2024年第6期7卷 167-175页

作者： Haiyan Fan Xinxin Zhang Jianhua Xiao Wenjie Chen Qiyuan Lin Zi Shyun Ng Yitao Lin Yi Su Ludi Pan Yipeng Su Shuaiyang Ren Haowen Liu Xuanzhang Li Yuegang Zhang State Key Laboratory of Low Dimensional Quantum physics and {1. of physics Tsinghua UniversityBeijing 100084China Frontier Science center for Quantum Information Beijing 100084China

Rechargeable magnesium metal batteries need an electrolyte that forms a stable and ionically conductive solid electrolyte interphase(SEI)on the ***,we used molecular dynamic simulation,density functional theory calculation,and X-ray photoelectron spectroscopy analysis to investigate the solvation structures and SEI compositions in electrolytes consisting of dual-salts,magnesium bis(trifluoromethanesulfonyl)imide(MgTFSI_(2)),and MgCl_(2),with different additives in 1.2-dimethoxyethane(DME)*** found that the formed[Mg_(3)(μ-Cl)_(4)(DME)mTFSI_(2)](m=3,5)inner-shell solvation clusters in MgTFSI_(2)-MgCl_(2)/DME electrolyte could easily decompose and form a MgO-and MgF_(2)-rich *** electron-rich inorganic species in the SEI,especially MgF_(2),turned out to be detrimental for Mg plating/*** reduce the MgF_(2)and MgO contents in SEI,we introduce an electron-deficient tri(2,2,2-trifluoroethyl)borate(TFEB)additive in the ***//Mg cells using the MgTFSI_(2)-MgCl_(2)/DME-TFEB electrolyte could cycle stably for over 400 h with a small polarization voltage of~1.0 *** with the presence of 800 ppm H_(2)O,the electrolyte with TFEB additive could still preserve its good electrochemical *** optimized electrolyte also enabled stable cycling and high-rate capability for Mg//Mo6S8 and Mg//CuS full cells,showing great potential for future applications.

关键词： electrolyte additives interfacial chemistry magnesium metal batteries solvation structure

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ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family

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National Science Review 2024年第2期11卷 81-93页

作者： Runzhe Xu Lixuan Xu Zhongkai Liu Lexian Yang Yulin Chen State Key Laboratory of Low Dimensional Quantum physics Department of PhysicsTsinghua University School of Physical Science and Technology Shanghai Tech University and CAS-Shanghai Science Research Center Shanghai Tech Laboratory for Topological physics Frontier Science center for Quantum Information Collaborative Innovation center of Quantum Matter department of {1. Clarendon LaboratoryUniversity of Oxford

In the past 5 years,there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n（where n=0,1.2…）.In particular,exfoliated thin films of MnBi2Te4have led to numerous experimental breakthroughs,such as the quantum anomalous Hall effect,axion insulator phase and high-Chern number quantum Hall effect without Landau ***,despite extensive efforts,the energy gap of the topological surface states due to exchange magnetic coupling,which is a key feature of the characteristic band structure of the system,remains experimentally *** electronic structure measured by using angle-resolved photoemission （ARPES） shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements,making it challenging to understand the transport results based on the electronic *** paper reviews the measurements of the band structure of MnBi2+2nTe4+3nmagnetic topological insulators using ARPES,focusing on the evolution of their electronic structures with temperature,surface and bulk doping and film *** aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3ncompounds and explore possible control of their topological properties.

关键词： magnetic topological insulator MnBi2Te4 electronic structure angle-resolved photoemission spectroscopy

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Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3（001. via metallic δ-doping

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National Science Review 2024年第3期11卷 119-127页

作者： Xiaotong Jiao Wenfeng Dong Mingxia Shi Heng Wang Cui Ding Zhongxu Wei Guanming Gong Yanan Li Yuanzhao Li Binjie Zuo Jian Wang Ding Zhang Minghu Pan Lili Wang Qi-Kun Xue State Key Laboratory of Low-Dimensional Quantum physics Department of Physics Tsinghua University School of physics&Information Technology Shaanxi Normal University Beijing Academy of Quantum Information Sciences department of {1. Southern University of Science and Technology International center for Quantum Materials School of Physics Peking University department of {1. The Pennsylvania State University Collaborative Innovation center of Quantum Matter Hefei National Laboratory

Superconductivity transition temperature（Tc） marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii–Kosterlitz–Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3（001., although the pairing temperature（Tp） is revealed to be 65–83 K by using spectroscopy characterization, the measured zero-resistance temperature（Tc0） is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3（001. surface, in which Tc0is enhanced by 1. K with a narrowed transition width ΔTc～8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3（001. surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.

关键词： monolayer FeSe interface superconductivity δ-doping zero-resistance temperature superconductivity transition temperature

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Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

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National Science Review 2024年第3期11卷 100-107页

作者： Feng Xue Yusheng Hou Zhe Wang Zhiming Xu Ke He Ruqian Wu Yong Xu Wenhui Duan Beijing Academy of Quantum Information Sciences State Key Laboratory of Low Dimensional Quantum physics Department of Physics Tsinghua University Guangdong Provincial Key Laboratory of Magnetoelectric physics and Devices Center for Neutron Science and Technology School of Physics Sun Yat-sen University State Key Laboratory of Surface physics Key Laboratory of Computational Physical Sciences and Department of PhysicsFudan University Frontier Science center for Quantum Information department of {1. and Astronomy University of California-Irvine Tencent Quantum Laboratory Tencent Technology(Shenzhen)Co.Ltd RIKEN center for Emergent Matter Science(CEMS) Institute for Advanced Study Tsinghua University

The quantum anomalous Hall effect（QAHE） has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C = ±1.and the out-of-plane magnetization induced QAHE with high Chern numbers C = ±3 can be realized in a single material candidate, which is composed of van der Waals（vdW）coupled Bi and MnBi2Te4monolayers. The switching between different phases of QAHE can be controlled in multiple ways, such as applying strain or（weak） magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.

关键词： quantum anomalous Hall effect topological quantum phase transition van der Waals heterostructures tunable Chern number high Chern number

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Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown Mn Bi2Te4 thin films

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National Science Review 2024年第2期11卷 24-32页

作者： Yunhe Bai Yuanzhao Li Jianli Luan Ruixuan Liu Wenyu Song Yang Chen Peng-Fei Ji Qinghua Zhang Fanqi Meng Bingbing Tong Lin Li Yuying Jiang Zongwei Gao Lin Gu Jinsong Zhang Yayu Wang Qi-Kun Xue Ke He Yang Feng Xiao Feng State Key Laboratory of Low Dimensional Quantum physics Department of Physics Tsinghua University Institute of physics Chinese Academy of Sciences School of Materials Science and Engineering Tsinghua University Beijing Academy of Quantum Information Sciences Frontier Science center for Quantum Information Hefei National Laboratory Southern University of Science and Technology

The intrinsic magnetic topological insulator MnBi2Te4provides a feasible pathway to the high-temperature quantum anomalous Hall（QAH） effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4thin flakes, it remains a big challenge to achieve molecular beam epitaxy（MBE）-grown MnBi2Te4thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4and to find a way out of the big difficulty in obtaining MnBi2Te4samples showing quantized transport properties.

关键词： intrinsic magnetic topological insulator quantized anomalous Hall resistivity molecular beam epitaxy quantized transport property

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Creation and annihilation of artificial magnetic skyrmions with the electric field

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Chinese physics B 2024年第3期33卷 132-137页

作者：程军孙亮张一可吉同舟曹荣幸缪冰锋赵永刚丁海峰 National Laboratory of Solid State Microstructures and department of {1. Nanjing UniversityNanjing 210093China Collaborative Innovation center of Advanced Microstructures Nanjing UniversityNanjing 210093China department of {1. State Key Laboratory of Low-Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China Frontier Science center for Quantum Information Tsinghua UniversityBeijing 100084China College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhou 225127China

Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field,casting strong potentials for the device *** this work,we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic *** find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic *** addition,we also demonstrate controllable manipulation of individual skyrmion,which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.

关键词： skyrmions magnetic anisotropy micromagnetic simulations

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