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Crystal Thermal Transport in Altermagnetic RuO2

Physical Review Letters 2024年第5期132卷 056701-056701页

作者： Xiaodong Zhou Wanxiang Feng Run-Wu Zhang Libor Šmejkal Jairo Sinova Yuriy Mokrousov Yugui Yao 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 Laboratory of Quantum Functional Materials Design and Application School of Physics and Electronic Engineering Jiangsu Normal University Xuzhou 221116 China Institute of Physics Johannes Gutenberg University Mainz 55099 Mainz Germany Institute of Physics Czech Academy of Sciences Cukrovarnická 10 162 00 Praha 6 Czech Republic Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARA 52425 Jülich Germany

We demonstrate the emergence of a pronounced thermal transport in the recently discovered class of magnetic materials—altermagnets. From symmetry arguments and first-principles calculations performed for the showcase altermagnet, RuO2, we uncover that crystal Nernst and crystal thermal Hall effects in this material are very large and strongly anisotropic with respect to the Néel vector. We find the large crystal thermal transport to originate from three sources of Berry’s curvature in momentum space: the Weyl fermions due to crossings between well-separated bands, the strong spin-flip pseudonodal surfaces, and the weak spin-flip ladder transitions, defined by transitions among very weakly spin-split states of similar dispersion crossing the Fermi surface. Moreover, we reveal that the anomalous thermal and electrical transport coefficients in RuO2 are linked by an extended Wiedemann-Franz law in a temperature range much wider than expected for conventional magnets. Our results suggest that altermagnets may assume a leading role in realizing concepts in spin caloritronics not achievable with ferromagnets or antiferromagnets.

关键词： Magnetism Nernst effect Thermal Hall effect Topological materials First-principles calculations

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Penetration damaging behavior of TB17 titanium alloy 20th

Penetration damaging behavior of TB17 titanium alloy

引用

20th Chinese Materials Conference, CMC 2019

作者： Li, Jing Xin, Yunpeng Jiang, Tao Wang, Xinnan Zhu, Zhishou Beijing Institute of Aeronautical Materials Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys Beijing100095 China

ISBN: (纸本)9783035715668

The damage behavior of TB17 titanium alloy with ultra-high strength was studied by 12.7mm diameter armor piercing test. The damage characteristics and mechanism of damaging were analyzed by the observation of damage morphology of target board. The results indicated that the opening area was irregular at the opening stage, the internal wall turtle-shell-like or poly-porous, a few cracks and no adiabatic shear band was observed. The zone was parabolic at the penetrating stage, the internal wall was granular or river pattern, the adiabatic shear bands and fragments existed around the crater. A large number micro-pores and micro-cracks originating from the adiabatic shear bands expanded, forming macroscopic cracks. Finally, the target board fractured. © 2020 Trans Tech Publications Ltd, Switzerland.

关键词： Titanium alloys

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Investigation of Transport Models of Radionuclides in Various Water Environments 29

Investigation of Transport Models of Radionuclides in Variou...

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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Qu, Zhengzhe Nie, Baojie Wang, Liang Xie, Feng Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety Ministry of Education Tsinghua University Beijing100084 China College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing211106 China School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment Beijing100082 China State Environ. Protect. Key Lab. of Nucl. and Radiation Safety Regulatory Simulation and Validation Beijing100082 China

ISBN: (纸本)9780791886502

Concerning the Fukushima nuclear accident, many radionuclides were released into the marine environment, which caused contamination of many parts of the world through ocean circulation. Regarding inland nuclear power plants, freshwater habitats such as reservoirs and rivers could also be polluted by the radioactive effluents. Several models were developed to track radionuclide transport in the water environment. However, the applicability and characteristics of these models were not fully identified and compared, particularly for the different water environments. In this study, the research progress and application examples of radionuclide transport models in rivers and oceans in recent years are systematically summarized, and the methods for simulating radionuclide transport behavior in various water environments are compared. An adequate model is expected to be instrumental in assessing radioactive pollution in various water environments. © 2022 by ASME.

关键词： Radioisotopes

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SAR image despeckling via Lp norm regularization

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High technology Letters 2022年第2期28卷 190-196页

作者： HAN Chengde CUI Yingzi HUANG Ying GUO Mingqiang LIU Zheng WU Liang Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural ResourcesShenzhen 518034P.R.China School of Geography and Information Engineering China University of GeosciencesWuhan 430074P R.China Hubei Geomatics Technology Group Stock Co. Ltd..Wuhan 430074P R.China Wuhan Zondy Advanced Technology Institute Co. Ltd.'Wuhan 430074P R'China National Engineering Research Center of Geographic Information System Wuhan 430074P R.China

Synthetic aperture radar(SAR) image despeckling has been an attractive problem in remote *** main challenge is to suppress speckle while preserving edges and preventing unnatural artifacts(such as annoying artifacts in homogeneous regions and over-smoothed edges).To address these problems,this paper proposes a new variational model with a nonconvex nonsmooth Lp(0

关键词： synthetic aperture radar(SAR)image speckle nonconvex nonsmooth regularization variational method alternating direction method of multiplier(ADMM)

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The impacts of socioeconomic development and climate change on long-term nutrient dynamics: A case study in Poyang Lake

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Science of the Total Environment 2024年 957卷 177843页

作者： Zhang, Xiaoyu Zhang, Shuhui Fang, Le Zhang, Cheng Li, Xia Advanced Interdisciplinary Institute of Environment and Ecology Beijing Normal University Zhuhai519087 China Advanced Institute of Natural Sciences Beijing Normal University Zhuhai519087 China State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing100875 China Key Laboratory of Coastal Water Environmental Management and Water Ecological Restoration of Guangdong Higher Education Institutes Beijing Normal University Zhuhai519087 China Instrumentation and Service Center for Science and Technology Beijing Normal University Zhuhai519087 China Guangdong Provincial Key Laboratory of Wastewater Information Analysis and Early Warning Beijing Normal University Zhuhai519087 China

The anthropogenic activities associated with rapid socioeconomic development affect global climate change and the water quality of lake ecosystems. However, the impacts of socioeconomic and climate changes on lake nutrient dynamics require additional study. In this study, we used a long-term dataset (1987–2021) of Poyang Lake to identify the nutrient dynamics and assess the impacts of social and climatic factors on nutrient concentrations. The filtering trajectory method (FTM) suggested that in Poyang Lake, nutrients first increased and then decreased, with TP reaching its highest value of 157 μg/L in 2015. The study employs a combination of structural equation modeling (SEM) and FTM to identify the complex interactions between socio-economic and climatic factors affecting nutrient concentrations in Poyang Lake. The SEM results revealed that socioeconomic factors rather than climate change determined the long-term changes in TN and TP. Additionally, FTM results verified that GDP, urbanization (Ur) and P-fertilizer (Pfer) were the key drivers of TN;Ur, population (P), and sewerage treatment rate (STR) were the primary factors of TP. Through generalized additive models (GAMs), we observed that GDP accounted for 86 % of the temporal variability in TN and 45.7 % of that in TP, exhibiting inverted U-shaped relationships with both TN and TP. Air temperature (AT), a climatic factor accounted for only 44.6 % and 14.8 % of the variation in TN and TP, respectively. In addition, Pfer explained 66.0 % of the variation in TN, and STR explained 50.4 % of the variation in TP with a peak TP at the STR threshold of approximately 80 %. Our findings highlight the importance of Pfer and STR as critical indicators for watershed nutrient management. The identification of key temporal drivers and nutrient trajectories provides a scientific basis for developing management strategies. The results highlight coordinated control strategies for water pollution and carbon reduction as essential

关键词： Lake pollution

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Capacitor Voltage Balancing Strategy Based on Zero-Sequence Voltage Injection for Half-Wave Commutated Modular Multilevel Converter

Capacitor Voltage Balancing Strategy Based on Zero-Sequence ...

引用

International Conference on Power Electronics and Motion Control (IPEMC)

作者： Nan Fu Bao Liu Yunfei Xu Sitong Zhu Kui Wang Yongdong Li Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd Changping Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang China

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

Half-wave commutated modular multilevel converter (HWC-MMC) is suitable for high-voltage large-capacity AC-AC conversion, and an appropriate capacitor voltage balancing strategy is essential. This paper analyzes the condition of capacitor voltage balancing and proposes a capacitor voltage balancing strategy based on optimal zero-sequence voltage injection using the model predictive control. Finally, the simulation is carried out to verify the proposed strategy.

关键词： Multilevel converters Voltage fluctuations Capacitors High-voltage techniques Power system harmonics Power electronics Steady-state

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Prediction of fully metallic σ-bonded boron framework induced high superconductivity above 100 K in thermodynamically stable Sr2B5 at 40 GPa

arXiv

引用

arXiv 2023年

作者： Yang, Xin Zhao, Wenbo Ma, Liang Lu, Wencheng Zhong, Xin Xie, Yu Liu, Hanyu Ma, Yanming Key Laboratory of Material Simulation Methods & Software Ministry of Education College of Physics Jilin University Changchun130012 China State Key Laboratory for Superhard Materials College of Physics Jilin University Changchun130012 China International Center of Future Science Jilin University Changchun130012 China Key Laboratory of Physics and Technology for Advanced Batteries Ministry of Education College of Physics Jilin University Changchun130012 China

Metal borides have been considered as potential high-temperature superconductors since the discovery of record-holding 39 K superconductivity in bulk MgB2. In this work, we identified a superconducting yet thermodynamically stable F(Equation presented)3m Sr2B5 at 40 GPa with a unique covalent sp3-hybridized boron framework through extensive first-principles structure searches. Remarkably, solving the anisotropic Migdal-Eliashberg equations resulted in a high superconducting critical temperature (Tc) around 100 K, exceeding the boiling point (77 K) of liquid nitrogen. Our in-depth analysis revealed that the high-temperature superconductivity mainly originates from the strong coupling between the metalized σ-bonded electronic bands and E phonon modes of boron atoms. Moreover, anharmonic phonon simulations suggest that F(Equation presented)3m Sr2B5 might be recovered to ambient pressure. Our current findings provide a prototype structure with a full σ-bonded boron framework for the design of high-Tc superconducting borides that may expand to a broader variety of lightweight compounds. © 2023, CC BY.

关键词： High temperature superconductors

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3d Non-Synchronous Measurements of the Spherical Harmonic Domain with the Open Spherical Microphone Array

SSRN

引用

SSRN 2023年

作者： Yu, Liang Liu, Huimin Chu, Ning Yang, Weihua School of Civil Aviation Northwestern Polytechnical University Xi’an710072 China College of Mathematics Taiyuan University of Technology Jinzhong030600 China Zhejiang Shangfeng Special Blower Co. Ltd Shaoxing312352 China State Key Laboratory of Airliner Integration Technology and Flight Simulation Shanghai200126 China Zhejiang University China

The width of the mainlobe in the spherical harmonic domain (SHD) acoustic imaging is mainly influenced by the microphone aperture and number. A research method proposed in this paper is to introduce the non-synchronous measurements (NSM) into the SHD in order to further improve the resolution of acoustic imaging in the spherical harmonic domain. The NSM is a sequential measurement technique that uses a prototype array to scan the sound source in some fixed positions, which can approximate the measurement results of large apertures and increased microphone density. The main contributions of this paper are: (1) the NSM technology is successfully merged into the SHD;(2) The spherical harmonic beamforming of NSM (NSM-SHB) and the sparse Bayesian learning of NSM in the SHD (NSM-SBL-SHD) methods are proposed. The effectiveness of the proposed methods is verified by simulation and loudspeaker experiments. The results demonstrate that the resolution of acoustic imaging is both improved by the NSM-SHB and NSM-SBL-SHD in the middle and low frequencies compared with the single measurement. Meanwhile, the computational speed of these two methods is further improved compared to conventional 3D acoustic imaging. © 2023, The Authors. All rights reserved.

关键词： Spheres

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Interfacial Thermal Transport and Energy Dissipation in Multilayer PdSe2 Field Effect Transistors

引用

advanced Materials 2025年第0期 e2503264页

作者： Xie, Jiaqiu Yu, Zehao Sun, Yuanchen Gan, Qikang Liu, Chenhan Wang, Lei Zhang, Lifa Zhao, Yunshan Phonon Engineering Research Center of Jiangsu Province Ministry of Education Key Laboratory of NSLSCS Center for Quantum Transport and Thermal Energy Science Institute of Physics Frontiers and Interdisciplinary Sciences School of Physics and Technology Nanjing Normal University Nanjing210023 China National Laboratory of Solid-State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Micro- and Nano-scale Thermal Measurement and Thermal Management Laboratory Jiangsu Key Laboratory for Numerical Simulation of Large-Scale Complex Systems School of Energy and Mechanical Engineering Nanjing Normal University Nanjing210046 China

The continuous miniaturization of 2D electronic circuits results in increased power density during device operation, leading to heat localization and placing higher demands on their performance thresholds. The risk to thermal breakdown and subsequent damage, due to the energy dissipation in the 2D semiconductor field-effect transistors (FETs) supported on the bulk substrates, represents a significant challenge in maintaining their optimal performance. Herein, this study investigates energy dissipation behavior in multilayer PdSe2 FETs for the first time. The high-field breakdown behavior is firstly studied in multilayer PdSe2 FETs on SiO2/Si substrates, where a maximum current density of ≈2.74 MA cm−2 is observed, which is comparable to that of multilayer black phosphorus FET and significantly higher—by about five times—than that of multilayer MoS2 FET. Additionally, the thermal boundary conductance (TBC) of PdSe2/SiO2 interface is measured at room temperature using Raman thermometry. The TBC is found to be ≈12–13 MW m−2 K−1, which is relatively low compared to the other known solid–solid interfaces, indicating that enhancing the performance of PdSe2 FETs can be possible by optimizing the TBC at the PdSe2/SiO2 interface. These findings provide valuable insights for design of high-quality and high-performance PdSe2 electronic and optoelectronic devices. © 2025 Wiley-VCH GmbH.

关键词： Multilayers

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Generation of complete graph states in a spin-1/2 Heisenberg chain with a globally optimized magnetic field

arXiv

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arXiv 2024年

作者： Li, X.X. Li, D.X. Shao, X.Q. Sino-European Institute of Aviation Engineering Civil Aviation University of China Tianjin300300 China College of Physics Science and Technology Shenyang Normal University Shenyang110034 China Center for Quantum Sciences School of Physics Northeast Normal University Changchun130024 China Center for Advanced Optoelectronic Functional Materials Research Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education Northeast Normal University Changchun130024 China

Graph states possess significant practical value in measurement-based quantum computation, with complete graph states that exhibit exceptional performance in quantum metrology. In this work, we introduce a method for generating multiparticle complete graph states using a spin-1/2 Heisenberg XX chain subjected to a time-varying magnetic field, which applies to a wide range of systems. Our scheme relies exclusively on nearest-neighbor interactions between atoms, with real-time magnetic field formation facilitated by quantum optimal control theory. We focus specifically on neutral-atom systems, finding that multiparticle complete graph states with N = 3 ∼ 6 can be achieved in less than 0.25 µs, using a hopping amplitude of J/(2π) = −2.443 MHz. This assumes an initial state provided by an equal-weight superposition of all spin states that are encoded by the dipolar-interacting Rydberg states. Furthermore, we thoroughly address various experimental imperfections and showcase the robustness of our approach against atomic vibrations, fluctuations in pulse amplitude, and spontaneous emission of Rydberg states. Taking into account the common occurrence of disturbances in the experimental setups of neutral-atom systems, our one-step strategy to achieve such graph states emerges as a viable alternative to techniques based on controlled-Z gates. © 2024, CC BY.

关键词： Rydberg states

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