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Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

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Chinese Physics B 2024年第4期33卷 181-186页

作者：陈紫雯张焱马平徐中堂李宇龙王越路建明马衍伟甘子钊 Applied superconductivity Research Center Peking UniversityBeijing 100871China State Key Laboratory for Artificial Microstructure and Mesoscopic Physics Peking UniversityBeijing 100871China Institute of Condensed Matter Physics School of PhysicsPeking UniversityBeijing 100871China Yangtze Delta Institute of Optoelectronics Peking UniversityBeijing 100871China Key Laboratory of Applied superconductivity Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190China

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great *** this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation *** junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)*** J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film *** Shapiro steps are observed under 10 GHz microwave *** above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

关键词： focused helium ion beam Co doped BaFe_(2)As_(2) Josephson junction

Absence of BCS–BEC crossover in FeSe0.45Te0.55 superconductor

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Chinese Physics B 2024年第7期33卷 89-96页

作者：贾俊杰谷亚东殷超辉束英杰陈逸雯史聚民张杏陈浩苗泰民任晓琳梁波朱文培蔡能张丰丰张申金杨峰王志敏彭钦军许祖彦毛寒青刘国东任治安赵林周兴江 National Laboratory for superconductivity Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Technical Institute of Physics and Chemistry Chinese Academy of Sciences Songshan Lake Materials Laboratory

In iron-based superconductor Fe（Se,Te）, a flat band-like feature near the Fermi level was observed around the Brillouin zone center in the superconducting state. It is under debate whether this is the evidence on the presence of the BCS–BEC[Bardeen–Cooper–Schrieffer（BCS）, Bose–Einstein condensation（BEC）] crossover in the superconductor. High-resolution laser-based angle-resolved photoemission measurements are carried out on high quality single crystals of FeSe0.45Te0.55superconductor to address the issue. By employing different polarization geometries, we have resolved and isolated the dyz band and the topological surface band, making it possible to study their superconducting behaviors separately. The dyz band alone does not form a flat band-like feature in the superconducting state and the measured dispersion can be well described by the BCS picture. We find that the flat band-like feature is formed from the combination of the dyz band and the topological surface state band in the superconducting state. These results reveal the origin of the flat band-like feature and rule out the presence of BCS-BEC crossover in Fe（Se,Te） superconductor.

关键词： ARPES BCS-BEC crossover electronic structure FeSe0.45Te0.55 superconducting gap

引入超导带材堆叠块体的混合眼型高温超导磁体的力学特性分析

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Acta Mechanica Sinica 2024年第4期40卷 27-37页

作者：廖恒沛袁炜嘉张玟 Applied superconductivity Laboratory Department of Electronics and Electrical EngineeringUniversity of StrathclydeGlasgowG11XQUnited Kingdom

高温超导磁体具有零电阻特性,通过适当的磁化过程,就可以在没有外部电源的情况下保持强磁场.使用商用高温超导带制造的眼型高温超导磁体已经证明了其具有稳定的强磁场捕获能力,并且相对于传统超导块材,其尺寸更加灵活.然而,在场冷磁化... 详细信息

高温超导磁体具有零电阻特性,通过适当的磁化过程,就可以在没有外部电源的情况下保持强磁场.使用商用高温超导带制造的眼型高温超导磁体已经证明了其具有稳定的强磁场捕获能力,并且相对于传统超导块材,其尺寸更加灵活.然而,在场冷磁化过程中,由洛伦兹力引起应力应变可能会对磁体造成损伤.因此,在本论文的研究中,建立并验证了三维数值计算模型,以研究混合眼型高温超导磁体中的应力和应变.计算了场冷磁化下磁体的应力分布,并讨论了样品的固定方法对应力集中和应变的影响.研究还发现,增强中心捕获磁场的高温超导带材堆叠块体在磁化过程中受到不平衡的洛伦兹力,这是由于眼型磁体的不对称捕获磁场而导致的,此不平衡力产生在高温超导堆叠中的不对称应力分布.这些发现为眼型高温超导磁体的机械行为提供了重要的见解,可以指导其设计的优化,以适应各种应用,如核磁共振、磁悬浮和高温超导电机等.

关键词：高温超导磁体高温超导带材零电阻特性磁化过程洛伦兹力高温超导电机外部电源不平衡力

Short circuit analysis of a fault-tolerant current-limiting high temperature superconducting transformer in a power system in presence of distributed generations

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superconductivity 2024年第1期9卷 74-86页

作者： Alireza Sadeghi Shahin Alipour Bonab Wenjuan Song Mohammad Yazdani-Asrami Propulsion Electrification&Superconductivity GroupAutonomous Systems&Connectivity DivisionJames Watt School of EngineeringUniversity of GlasgowGlasgow G128QQUnited Kingdom

Power transformers are key elements for the safe and reliable delivery of electrical energy generated by renewable energy resources to consumers via transmission ***‐tolerant current‐limiting High Temperature Superconducting(FTCL HTS)transformers are type of superconducting transformers that tolerate fault for seconds and limit the fault current without the threat of burnout or delamination of tapes and deformation of *** this paper,the fault performance of a FTCL HTS transformer in a standard IEEE power system is *** studied transformer is a 50 MVA 132 kV/13.8 kV transformer where both windings are made up of HTS *** understudied power system consists of two microgrids with distributed *** of the power in microgrids is supplied by the upstream grid which is connected to the microgrids through the HTS *** fault scenarios have been considered in this power system,in each one of these scenarios,a fault happens in one of the *** considered fault scenarios have an approximate fault current of 18x to 23x of the rated current in the secondary *** showed that insulated windings in FTCL HTS transformers could substantially reduce the peak temperature of the HTS windings,compared to bare ***,post‐fault loading is imposed on the HTS windings,to observe their performance against the current increase after fault *** this case,for the first scenario of the faults,the FTCL HTS transformer could tolerate 192%of post‐fault overloading,while this number for the second fault scenario is 170%.Finally,the impact of post‐fault loading on the full recovery time was discussed.

关键词： Fault Energy Heat dissipation Heat transfer Insulation Recovery Time Temperature rise

Negligible normal fluid in superconducting state of heavily overdoped Bi_(2)Sr_(2)CaCu_(2)O_(8+δ) detected by ultra-low temperature angle-resolved photoemission spectroscopy

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Chinese Physics B 2024年第7期33卷 562-567页

作者：殷超辉汪清泓解于洋陈逸雯刘俊豪杨鉴刚贾俊杰张杏吕文凯闫宏涛戎洪涛张申金王志敏宗楠刘丽娟李如康王晓洋张丰丰杨峰彭钦军许祖彦刘国东毛寒青赵林李昕彤周兴江 National Laboratory for superconductivity Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Technical Institute of Physics and Chemistry Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

In high temperature cuprate superconductors,it was found that the superfluid density decreases with the increase of hole *** natural question is whether there exists normal fluid in the superconducting state in the overdoped *** this paper,we have carried out high-resolution ultra-low temperature laser-based angle-resolved photoemission measurements on a heavily overdoped Bi2212 sample with a T_(c) of 48 *** find that this heavily overdoped Bi2212 remains in the strong coupling regime with 2Δ_(0)/(k_(B)T_(c))=*** single-particle scattering rate is very small along the nodal direction(~5 meV) and increases as the momentum moves from the nodal to the antinodal regions.A hard superconducting gap opening is observed near the antinodal region with the spectral weight at the Fermi level fully suppressed to *** normal fluid is found to be negligibly small in the superconducting state of this heavily overdoped *** results provide key information to understand the high T_(c) mechanism in the cuprate superconductors.

关键词： cuprate superconductor angle-resolved photoemission spectroscopy electronic structure

40-meter-long REBCO tapes with critical current over 4,000 A/12 mm at 4.2 K and 13 T by advanced MOCVD

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superconductivity 2024年第1期9卷 29-34页

作者： Mahesh Paidpilli Chirag Goel Bhabesh Sarangi Siwei Chen Eduard Galstyan Jan Jaroszynski Griffin Bradford Dmytro Abraimov Venkat Selvamanickam Department of Mechanical Engineering Advanced Manufacturing InstituteTexas Center for SuperconductivityUniversity of HoustonHoustonTexasUSA AMPeers LLC HoustonTexasUSA National High Magnetic Field Laboratory TallahasseeFloridaUSA

REBa_(2)Cu_(3)O_(7−δ)(REBCO,RE=rare earth)tapes doped with 5%and 15%Zr have been scaled up to lengths more than 40 m in a pilot‐scale advanced metal organic chemical vapor deposition(A‐MOCVD)*** precursor compositions used for the long tapes were guided by a study of the influence of(Ba+dopant)/Cu content on the critical current density(Jc)of 5 and 15 mol.%Hf‐and Zr‐added tapes at 4.2 K and 13 *** 40‐mlong tapes exhibited a critical current(Ic)over 4,000 A/12 mm at 4.2 K and 13 T as well as over 1,400 A/12 mm at 20 K and 20 *** critical current densities of a 40‐m‐long tape doped with 5%Zr at 4.2 K measured at the National High Magnetic Field Laboratory(NHMFL)were>10 MAcm^(−2)and>5 MAcm^(−2)at 14 T and 30 T,respectively,which are over three times those of commercial REBCO *** infield Jc of 5%Zradded 40‐m‐long tapes was similar to those of previously‐reported high‐performance short samples made with 15%Zr or *** results demonstrate the excellent potential of A‐MOCVD for manufacturing high Ic REBCO tapes for use in ultrahigh‐field magnet applications.

关键词： High‐temperature superconductors MOCVD REBCO Critical current

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计算超导螺线管磁体中电磁应力的解析方法

Acta Mechanica Sinica 2024年第4期40卷 4-20页

作者： Jeonghwan Park Kibum Choi Yufan Yan Jaemin Kim Seungyong Hahn Department of Electrical and Computer Engineering Seoul National UniversitySeoul08826Republic of Korea Applied superconductivity Center and Electric Power Institute Seoul National UniversitySeoul08826Republic of Korea

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来... 详细信息

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来的自保护行为至关重要.根据关键磁体设计参数(如目标中心场、背景磁场、内外绕组直径和外部径向堆叠),我们给出了可以从解析上确定高场超导磁体具有压缩径向应力的电磁-力学条件.本文提出的方法可以识别干绕线圈中径向匝间接触行为的3种不同模式:(1)完全分离;(2)完全接触;以及(3)混合模式(即部分分离和接触).文章随后提出一种使用完全压缩径向应力电磁-力学条件来计算干绕线圈中应力分布的解析方法.并通过有限元分析示例验证了解析方法与数值方法的良好一致性.文章结果可以帮助磁体工程师在早期设计阶段更好地概览高场超导磁体的电磁-力学行为.

关键词：高温超导背景磁场径向应力力学条件拉伸应力匝间接触行为混合模式

Challenges and strategies of chlorine inhibition in anode systems for seawater electrolysis

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Science China Chemistry 2024年

作者： Chuqiang Huang Zhouzhou Wang Shaojun Cheng Yunpeng Liu Binglu Deng Shaoyi Xu Luo Yu Ying Yu School of Materials Science and Hydrogen Energy Foshan University Institute of Nanoscience and Nanotechnology College of Physical Science and TechnologyCentral China Normal University Department of Physics and Texas Center for superconductivity at the University of Houston (TcSUH) University of Houston Laboratory of Solar Fuel Faculty of Materials Science and ChemistryChina University of Geosciences

Seawater electrolysis for green hydrogen production is one of the key technologies for achieving carbon ***,in anode systems,the chloride ions （Cl-） in seawater will trigger an undesired chlorine evolution reaction （CER） that competes with an oxygen evolution reaction （OER）,resulting in inferior OER activity and ***,the corrosive Cl-and its derivative products will corrode anodes during seawater electrolysis,leading to poor ***,great efforts have been devoted to developing efficient strategies for chlorine inhibition to improve the activity,selectivity,and stability of anode ***,focusing on chlorine inhibition,we present a mini review to comprehensively and concisely summarize the recent progress in anode systems for boosting seawater *** particular,two strategies of physical and chemical regulation to inhibit Cl-are summarized in some representative ***,some challenges and future opportunities in anode systems for seawater electrolysis are *** mini review aims to shed light on designing highly efficient anode materials for seawater electrolysis.

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(Ba,K)Fe_(2)As_(2)铁基超导多芯线材的晶间耦合强化与性能提高

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Science China Materials 2024年第1期67卷 301-310页

作者：郭文文姚超熊颢杨鹏涂畅马衍伟 Key Laboratory of Applied superconductivity Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu ZhongkeJinan 250013China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

铁基超导材料在高场超导磁体领域具有很大的应用潜力,而研究具有高传输临界电流密度的多芯复合包套线材对于其实际应用至关重要.本研究基于粉末装管法,结合孔型轧制工艺和热等静压烧结工艺制备了多芯Cu/Ag复合包套(Ba,K)Fe_(2)As_(2)(Ba... 详细信息

铁基超导材料在高场超导磁体领域具有很大的应用潜力,而研究具有高传输临界电流密度的多芯复合包套线材对于其实际应用至关重要.本研究基于粉末装管法,结合孔型轧制工艺和热等静压烧结工艺制备了多芯Cu/Ag复合包套(Ba,K)Fe_(2)As_(2)(Ba-122)超导线材.通过对不同直径线材中Ba-122超导芯的质量密度、晶粒取向、晶粒尺寸、元素分布与线材的电流传输性能之间的关系进行系统研究,我们发现线径较小的样品中超导晶粒间的耦合得到了显著增强,其传输临界电流密度在4.2 K,10 T下达到3.3×10^(4)A cm^(-2),同时由于晶粒尺寸和超导芯丝的均匀性得到改善,其电流传输的一致性(n值)也获得有效提高.本研究为制备高性能、高度均匀的铁基超导多芯线材提供了一种可规模化的工艺路线,对促进铁基超导材料的高场强电应用有重要意义.

关键词：热等静压烧结孔型轧制晶粒取向临界电流密度晶粒间质量密度晶粒尺寸工艺路线