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Unusual metallic state in superconducting A15-type La4H23

National Science Review 2024年第12期11卷 94-103页

作者： Jianning Guo Dmitrii Semenok Grigoriy Shutov Di Zhou Su Chen Yulong Wang Kexin Zhang Xinyue Wu Sven Luther Toni Helm Xiaoli Huang Tian Cui State Key Laboratory of Superhard Materials College of Physics Jilin University Center for High Pressure Science and Technology Advanced Research (HPSTAR) Department of High-Temperature Superconductivity Skolkovo Institute of Science and Technology Skolkovo Innovation CenterComputational and Data Science and Engineering HochfeldMagnetlabor Dresden(HLD-EMFL) and Würzburg-Dresden Cluster of Excellence Helmholtz-Zentrum Dresden-Rossendorf(HZDR) School of Physical Science and Technology Ningbo University

Hydride superconductors continue to fascinate the communities of condensed matter physics and material scientists because they host the promising near room-temperature superconductivity. Current research has concentrated on the new hydride superconductors with the enhancement of the superconducting transition temperature（Tc）. The multiple extreme conditions（high pressure/temperature and magnetic field） will introduce new insights into hydride superconductors. The study of transport properties under very high magnetic fields facilitates the understanding of superconductivity in conventional hydride *** the present work, we report experimental evidence of an unusual metal state in a newly synthesized cubic A15-type La4H23that exhibits superconductivity with a Tc reaching 105 K at 118 GPa. A large negative magnetoresistance is observed in strong pulsed magnetic fields in the non-superconducting state of this compound below 40 K. Moreover, we construct the full magnetic phase diagram of La4H23up to 68 T at high pressure. The present work reveals anomalous electronic structural properties of A15-La4H23under high magnetic fields, and therefore has great importance with regard to advancing the understanding of quantum transport behaviors in hydride superconductors.

关键词： high-pressure superconductivity hydrides negative magnetoresistance

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Entropy-driven atomic activation in supercooled liquids and its link to the fragile-to-strong transition

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Science China(physics,Mechanics & Astronomy) 2023年第4期66卷 100-111页

作者： Wei Chu Zheng Wang Nannan Ren Bangshao Dong Jinhua Yu Pengfei Guan Yanhui Liu Yuanzheng Yue Lina Hu Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong University Jinan 250061China Beijing Computational Science Research Center Beijing 100193China Central Iron&Steel Research Institute Advanced Technology&Materials Co.Ltd.Beijing 100081China Institute of Physics Chinese Academy of SciencesBeijing 100190China Department of Chemistry and Bioscience Aalborg UniversityAalborg 9220Denmark

As a common but critical dynamic crossover in glass-forming liquids(GFLs),the discovery of fragile-to-strong(F-S)transition promises a novel route for understanding supercooled liquid and glass *** present work,for the first time,successfully realizes the quantitative prediction of the F-S transition in nine metallic glass-forming liquids,by a counter-intuitive approach that focuses on local atomic activation events,rather than relaxation,upon *** dynamic crossover originates from a disorder-to-order transition by self-regulating behavior of atomic position within a cage controlled by finite atomic activation events,due to the appearance of local cooperative motion of nearest neighborhood ***,the dominant role of entropy in this anomaly has been discovered,and the correspondence between the crossover of configuration entropy involved in activation events and the occurrence of F-S transition has been *** work implies that the feature of atomic energy fluctuations reflected by atomic activation events has a close linkage to complex dynamic behaviors of disordered systems.

关键词： metallic glass fragile-to-strong transition supercooled liquid entropy control

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Particle motion around luminous neutron stars: Effects of deviation from Schwarzschild spacetime

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Physical Review D 2024年第6期110卷 064010页

作者： Ronaldo S. S. Vieira Maciek Wielgus Centro de Ciências Naturais e Humanas Auf dem Hügel 69 D-53121 Bonn Germany Research Centre for Computational Physics and Data Processing Institute of Physics

We study trajectories of test particles around a luminous, static, spherically symmetric neutron star, under the combined influence of gravity and radiation. In general relativity, for Schwarzschild spacetime, an equilibrium sphere (the Eddington capture sphere) is formed for near-Eddington luminosities. We generalize these results to a broad class of static, spherical spacetimes. We also study the dynamics of particles in a strong radiation field in spherical spacetimes. The results are illustrated for two cases, Reissner-Nordström spacetime of a charged spherical object in general relativity and Kehagias-Sfetsos spacetime, arising from the Hořava-Lifshitz gravity theory. Our findings apply to neutron stars under gravitational field equations different from the vacuum Einstein field equations of general relativity, such as in modified theories of gravity, the only requirement being that test particles follow geodesics in the absence of the radiation field. The effects that we describe are, in principle, measurable through observations of x-ray bursts of neutron stars. Hence, detailed future studies could use such observations to test gravity theories in the strong-field regime, provided that the impact of the spacetime geometry can be disentangled from the astrophysical uncertainties.

关键词： Alternative gravity theories General relativity X ray bursts Neutron stars & pulsars

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Shielding technology and the bush initiative - Shielding for lunar and martian missions

Shielding technology and the bush initiative - Shielding for...

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AIAA Space 2005 Conference and Exposition

作者： Thibeault, Sheila A. Wilson, John W. Clowdsley, Martha S. Kiefer, Richard L. Orwoll, Robert A. Boone, Amanda Hu, Lucy Y. Huttenhower, Hillary A. Besal, Barbara H. Schulz, Meghan E. Yang, Sha O'Neill, Christopher A. Miller, Adriane K. NASA Langley Research Center Hampton VA 23681 College of William and Mary Williamsburg VA 23185 Advanced Materials and Processing Branch Mail Stop 226 Computational Structures and Materials Branch Mail Stop 388 Department of Chemistry Department of Physics

ISBN: (纸本)1563477386

Past space missions beyond the confines of Earth's protective magnetic field have been of short duration, and protection from the effects of solar particle events was of primary concern. Aluminum alloy structures provided sufficient protection to meet requirements to prevent early radiation syndrome and were further successfully employed as protection against trapped protons in low Earth orbit (LEO). Aluminum alloys have been the materials of choice for the first 40 years of the space program. The extension of operations beyond LEO to enable routine access to other interesting regions of space will require protection from the hazards of the accumulated exposures of Galactic Cosmic Rays (GCR), and efficient fragmentation of GCR ions with minimal production of secondary particles in shielding materials is essential to protecting the astronauts. Aliphatic polymer composites are the most efficient structural materials exhibiting significantly improved radiation shielding properties, but they are limited in meeting the requirements of the service environment. Aromatic polymer composites developed mainly for high-speed aircraft applications have improved thermal-mechanical properties over aluminum alloys, as well as improved radiation shielding performance. Aliphatic/aromatic hybrid polymers are being developed to give a range of thermal-mechanical properties. The development of functionally graded structures will provide optimum solutions to multifunctional materials requirements in the near-term space program, with far-term utility.

关键词： Magnetic shielding

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TOI-2005b: An Eccentric Warm Jupiter in Spin-Orbit Alignment

arXiv

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arXiv 2025年

作者： Bieryla, Allyson Dong, Jiayin Zhou, George Eastman, Jason D. Mayorga, L.C. Latham, David W. Carter, Brad Huang, Chelsea X. Quinn, Samuel N. Collins, Karen A. Abe, Lyu Beletsky, Yuri Brahm, Rafael Colón, Knicole D. Essack, Zahra Guillot, Tristan Henning, Thomas Hobson, Melissa J. Horne, Keith Jenkins, Jon M. Jones, Matías I. Jordán, Andrés Osip, David Ricker, George R. Rodriguez, Joseph E. Schulte, Jack Schwarz, Richard P. Seager, Sara Shporer, Avi Suarez, Olga Tan, Thiam-Guan Ting, Eric B. Triaud, Amaury Vanderburg, Andrew Villaseñor, Jesus Noel Vowell, Noah Watkins, Cristilyn N. Winn, Joshua N. Ziegler, Carl Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States University of Southern Queensland Centre for Astrophysics West Street ToowoombaQLD4350 Australia Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States Department of Astronomy University of Illinois at Urbana-Champaign UrbanaIL61801 United States The Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Rd LaurelMD20723 United States Observatoire de la Côte d’Azur UniCA Laboratoire Lagrange CNRS UMR 7293 CS 34229 06304 Nice cedex 4 France Las Campanas Observatory Carnegie Institution for Science Colina El Pino Casilla La Serena601 Chile Facultad de Ingeniería y Ciencias Universidad Adolfo Ibáñez Av. Diagonal las Torres 2640 Santiago Peñalolén Chile Millennium Institute for Astrophysics Chile Data Observatory Foundation Chile GreenbeltMD20771 United States Department of Physics and Astronomy The University of New Mexico 210 Yale Blvd NE AlbuquerqueNM87106 United States Max-Planck-Institut für Astronomie Königstuhl 17 Heidelberg69117 Germany SUPA Physics and Astronomy University of St. Andrews Fife ScotlandKY16 9SS United Kingdom NASA Ames Research Center Moffett FieldCA94035 United States European Southern Observatory Alonso de Córdova 3107 Vitacura Casilla Santiago19001 Chile Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02139 United States Department of Aeronautics and Astronautics MIT 77 Massachusetts Avenue CambridgeMA02139 United States Observatoire de la Côte d’Azur UniCA CNRS CS 34229 Nice06304 cedex 4

We report the discovery and characterization of TOI-2005 b, a warm Jupiter on an eccentric (e ∼ 0.59), 17.3-day orbit around a Vmag = 9.867 rapidly rotating F-star. The object was detected as a candidate by TESS and the planetary nature of TOI-2005 b was then confirmed via a series of ground-based photometric, spectroscopic, and diffraction-limited imaging observations. The planet was found to reside in a low sky-projected stellar obliquity orbit (λ =4.8+2−235 degrees) via a transit spectroscopic observation using the Magellan MIKE spectrograph. TOI-2005 b is one of a few planets known to have a low-obliquity, high-eccentricity orbit, which may be the result of high-eccentricity coplanar migration. The planet has a periastron equilibrium temperature of ∼ 2100 K, similar to some highly irradiated hot Jupiters where atomic metal species have been detected in transmission spectroscopy, and varies by almost 1000 K during its orbit. Future observations of the atmosphere of TOI-2005b can inform us about its radiative timescales thanks to the rapid heating and cooling of the planet. © 2025, CC BY.

关键词： Photometry

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Angular momentum for black hole binaries in numerical relativity

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Physical Review D 2023年第6期108卷 064019-064019页

作者： Ritesh Bachhar Richard H. Price Gaurav Khanna Department of Physics and Center for Computational Research University of Rhode Island Kingston Rhode Island 02881 USA and Department of Physics and Center for Scientific Computing and Data Research University of Massachusetts Dartmouth Massachusetts 02747 USA

The extensive catalog of waveforms, with details of binary black hole inspiral and merger, offer an opportunity to understand black hole interactions beyond the large separation regime. We envision a research program that focuses on the transfer of angular momentum from spin of the individual holes to the orbital angular momentum and the role of tidal coupling in the process. That analysis will require the formulation of an expression for the orbital angular momentum of a binary, an expression that is useful at small separations, since that regime is well out of the range of Newtonian approximations and is where tidal coupling should be most interesting. We report here such an expression, a binary orbital angular momentum based on numerical relativity results for quasicircular orbits, that agrees remarkably well with a similar quantity constructed with particle-perturbation techniques for the Kerr geometry.

关键词： General relativity Gravitational waves

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Benchmark Tests of Principal Fissile Nuclide data in JENDL-3 with Simple Fast Critical Assemblies

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Journal of Nuclear Science and Technology 1993年第11期30卷 1087页

作者： TIAN, Dongfeng HASEGAWA, Akira NAKAGAWA, Tsuneo KIKUCHI, Yasuyuki Nuclear Data Center Department of PhysicsTokai Research EstablishmentJapan Atomic Energy Research Institute A visiting scientist through STA Scientist Exchange Program from Institute of Applied Physics and Computational Mathematics

A series of benchmark tests was made to check the neutron nuclear data of main fissile nuclides (239Pu, 236U and 233U) of JENDL-3 for fast reactors. A total of nine critical assemblies were analyzed. They are assemblies of single material, high enrichment and simple geometry with small volume and therefore suitable for nuclear data testing. Criticality calculation was made by ANISN with S16P5 using the VITAMIN-J 175-energy-group. Discussions are made on ken, spectral indices at core center and leakage spectra. From the study, a problem was pointed out relating to the interpolation of secondary-neutron energy distributions for threshold reactions near the threshold energy point adopted in the original JENDL-3 and its remedy was proposed. By the benchmark tests of thus revised JENDL-3 (JENDL-3.1), it was shown that integral experiments for 239Pu and 235U cores were reproduced quite satisfactorily. On the contrary, it was revealed that large deviations for 233U cores from the experiment were due to uncertainties of the fission spectrum and the inelastic scattering cross sections, In the present work, sensitivity of "a" parameter (level density parameter) of Madland-Nix's fission spectrum formula to the integral data was extensively studied. Some recommendations are made to improve JENDL-3.1.

关键词： JENDL-3 fast reactors benchmarks neutrons nuclear data cross section plutonium-239 uranium-235 uranium-233 Madland-Nix's fission spectra k eff spectral index leakage spectra accuracy

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DeePMD-kit v3: A Multiple-Backend Framework for Machine Learning Potentials

arXiv

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arXiv 2025年

作者： Zeng, Jinzhe Zhang, Duo Peng, Anyang Zhang, Xiangyu He, Sensen Wang, Yan Liu, Xinzijian Bi, Hangrui Li, Yifan Cai, Chun Zhang, Chengqian Du, Yiming Zhu, Jia-Xin Mo, Pinghui Huang, Zhengtao Zeng, Qiyu Shi, Shaochen Qin, Xuejian Yu, Zhaoxi Luo, Chenxing Ding, Ye Liu, Yun-Pei Shi, Ruosong Wang, Zhenyu Bore, Sigbjørn Løland Chang, Junhan Deng, Zhe Ding, Zhaohan Han, Siyuan Jiang, Wanrun Ke, Guolin Liu, Zhaoqing Lu, Denghui Muraoka, Koki Oliaei, Hananeh Singh, Anurag Kumar Que, Haohui Xu, Weihong Xu, Zhangmancang Zhuang, Yong-Bin Dai, Jiayu Giese, Timothy J. Jia, Weile Xu, Ben York, Darrin M. Zhang, Linfeng Wang, Han School of Artificial Intelligence and Data Science Unversity of Science and Technology of China Hefei China AI for Science Institute Beijing100080 China DP Technology Beijing100080 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China State Key Lab of Processors Institute of Computing Technology Chinese Academy of Sciences Beijing100871 China University of Chinese Academy of Sciences Beijing China Baidu Inc. Beijing China Department of Computer Science University of Toronto TorontoON Canada Department of Chemistry Princeton University PrincetonNJ08540 United States University of Chinese Academy of Sciences Beijing100871 China State Key Laboratory of Physical Chemistry of Solid Surfaces iChEM College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China College of Integrated Circuits Hunan University Changsha410082 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center for Smart Materials and Device Integration School of Material Science and Engineering Wuhan University of Technology Wuhan430070 China College of Science National University of Defense Technology Changsha410073 China Hunan Key Laboratory of Extreme Matter and Applications National University of Defense Technology Changsha410073 China ByteDance Research Beijing100098 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education College of Chemistry Beijing Normal University Beijing100875 China Department of Geosciences Princeton University PrincetonNJ08544 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States IKKEM Fujian Xiamen361005 China Graduate

In recent years, machine learning potentials (MLPs) have become indispensable tools in physics, chemistry, and materials science, driving the development of software packages for molecular dynamics (MD) simulations and related applications. These packages, typically built on specific machine learning frameworks such as TensorFlow, PyTorch, or JAX, face integration challenges when advanced applications demand communication across different frameworks. The previous TensorFlow-based implementation of DeePMD-kit exemplified these limitations. In this work, we introduce DeePMD-kit version 3, a significant update featuring a multi-backend framework that supports TensorFlow, PyTorch, JAX, and PaddlePaddle backends, and demonstrate the versatility of this architecture through the integration of other MLPs packages and of Differentiable Molecular Force Field. This architecture allows seamless backend switching with minimal modifications, enabling users and developers to integrate DeePMD-kit with other packages using different machine learning frameworks. This innovation facilitates the development of more complex and interoperable workflows, paving the way for broader applications of MLPs in scientific research. Copyright © 2025, The Authors. All rights reserved.

关键词： Molecular dynamics

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Stabilizing oxygen vacancies and promoting electrostrain in leadfree potassium niobate-based piezoelectrics over wide temperature ranges

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Journal of Advanced Ceramics 2024年第12期13卷 1965-1973页

作者： Bingcheng Luo Wei Feng Suwei Dai Hongzhou Song Yunyi Wu Jie Zhang College of Science China Agricultural UniversityBeijing 100083China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China School of Materials Science and Technology China University of Geosciences BeijingBeijing 100083China Institute of Applied Physics and Computational Mathematics Beijing 100094China Research Center for Comprehensive Energy Technology CTG Science and Technology Research InstituteBeijing 100038China Research Center for Metamaterials Wuzhen LaboratoryJiaxing 314500China

Piezoelectric ceramics provide high strain and large driving forces in actuators.A large electrostrain can be realized by the introduction of point defects such as vacancies,interstitial defects,and substitution *** Mn doping,a significant increase in the reversible electrostrain from 0.05%to 0.17%could be achieved in potassium niobite lead-free piezoelectric *** origins of the large electrostrain were analyzed via in situ X-ray diffraction(XRD)under an electric *** electrostrain and other typical electrical properties of the samples were measured at various temperatures,which enabled the ceramics to perform under a very wide temperature range,such as−80–130℃ for the 0.5 mol%Mn-doped sample with low dielectric loss(≤0.02).More importantly,combined with characterizations of the defect behavior by thermally stimulated depolarization current(TSDC),the failure mechanisms of electrostrain in a hightemperature environment could be revealed,which was associated with synergistic damage to the defects caused by the electric field and high *** results can provide good ideas and a basis for the design of piezoelectric materials with good electrostrain stability over a wide temperature range.

关键词： piezoelectric ceramic lead-free point defect electrostrain thermally stimulated depolarization current(TSDC)

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Pionium as a source of false events in the K→πνν¯ decays

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Physical Review D 2020年第11期102卷 113005-113005页

作者： Peter Lichard Institute of Physics and Research Centre for Computational Physics and Data Processing Silesian University in Opava 746 01 Opava Czech Republic and Institute of Experimental and Applied Physics Czech Technical University in Prague 128 00 Prague Czech Republic

We suggest that the decay modes of kaons with a pion and a pionium (π+π− atom) in the final state can constitute a not yet considered background to the very rare decay K→πνν¯. In fact, a part of pioniums may escape the decay region before decaying into two π0s (or to π0π0γ in the case of excited pionium). To illustrate the importance of this background, we show that it may even explain, under some assumptions, the unexpected KL decay events that appeared in the KOTO experiment.

关键词： Particle decays Rare decays

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