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Numerical simulations on the AC loss of REBCO stacks under rotating magnetic fields

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superconductivity 2024年第3期11卷 34-44页

作者： Yuan Wang Jin Fang Timothy Haugan Rodney A.Badcock James G.Storey Zhenan Jiang School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China The Air Force Research Laboratory Aerospace Systems Directorate1950 Fifth St.Bldg 18Wright-Patterson AFBOH 45433United States of America Paihau-Robinson Research institute Victoria University of WellingtonWellingtonLower Hutt 5011New Zealand

AC loss presents a significant challenge for high-temperature superconducting (HTS) rotating machines. To date, the behaviour of total AC loss (Qtol) (with current) and magnetization loss (Qm) (without current) in a single HTS tape under rotating magnetic fields (RF) have been explored. However, a research gap remains in understanding how these findings translate to the more complex HTS windings of rotating machines. Further exploration is needed to understand the loss behaviour of more complex HTS structures, such as HTS stacks. In this work, Qtol and Qm, in the HTS stacks under RF and a perpendicular AC standing wave magnetic field are numerically investigated. Two different RF models are considered: one is the Uni-RF model, characterized by a uniform field with equal field amplitudes and phases at each position, and the other is a non-uniform field created by a rotating Halbach array, referred to as the Hal-RF model. The dependence of AC loss on parameters such as the number of tapes in the stacks, tape width (2a), and the inclination angle (α) of tapes, which refers to the angle between the normal direction of the stack and the vertical direction, have been explored. The number of tapes in the stacks ranges from 1 to 16, α ranges from 0° to 90°, and the tape width includes 4 mm and 40 mm. Additionally, different rotating field directions are also considered. Interestingly, the analytical values from Brandt and Indenbom equation for Q_(m) of a superconducting strip (BI-strip) are close to Q_(m) results of the stacks under the standing wave at high fields, while they are over twice as high as those in the Hal-RF model at 1 T. This suggests the BI-strip equation is not reliable for predicting Q_(m) under RF at high fields. We also show in the Hal-RF model that different rotation directions of the field lead to varying Q_(m) and Qtol when asymmetric Jc (B, θ) data are applied. Moreover, it has been observed that the inclination angle has no impact on Q_(m) under uni

关键词： Stacks Rotating magnetic field Magnetization loss Total AC loss finite element method(FEM)

Type-II Dirac Semimetal State in a Superconductor Tantalum Carbide

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Chinese Physics Letters 2020年第8期37卷 83-87页

作者： Zhihai Cui Yuting Qian Wei Zhang Hongming Weng Zhong Fang Beijing National Research Center for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and EnergyFujian Normal UniversityFuzhou 350117China Songshan Lake Materials Laboratory Dongguan 523808China

The exploration of topological Dirac semimetals with intrinsic superconductivity can be a most plausible way to discover topological *** propose that type-II Dirac semimetal states exist in the band structure of TaC,a well-known s-wave superconductor,by using the first-principles calculations and theκ· p effective *** tilted gapless Dirac cones,which are composed of Ta d and C p orbitals and are protected by C4v symmetry,are found to be below the Fermi *** bands from Ta d orbitals are greatly coupled with the acoustic modes around the zone boundary,indicating their significant contribution to the *** relatively high transition temperature^10.5 K is estimated to be consistent with the experimental *** bring the type-II Dirac points close to chemical potential,hole doping is *** seems to decrease the transition temperature a lot,making the realization of topological superconductivity impossible.

关键词： Dirac topological superconductivity

FeTe1-xSex monolayer films： towards the realization of high-temperature connate topological superconductivity

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Science Bulletin 2017年第7期62卷 503-507页

作者： Xun Shi Zhi-Qing Han Pierre Richard Xian-Xin Wu Xi-Liang Peng Tian Qian Shan-Cai Wang Jiang-Ping Hu Yu-Jie Sun Hong Ding Beijing National Laboratory for Condensed Matter Physics and institute of Physics Chinese Academy of Sciences Beijing 100190 China Department of Physics Bering Key Laboratory of Opto-Electronic Functional Materials and Micro-nano Devices Renmin University of China Beijing 100872 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China

We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_*** superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by ***,the band gap between the electron-and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted by theoretical *** results provide a clear experimental indication that the FeTe_(1-x)Se_x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically.

关键词： Topological superconductivity Iron-based superconductors Thin film

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高温超导约瑟夫森结阵列的相位锁定

低温与超导 2008年第3期36卷 1-3,36页

作者：何明宋凤斌岳宏卫赵新杰左涛方兰阎少林 A.M.Klushin N.Klein 南开大学电子科学系天津300071 institute of Bio-and Nanosystems Forschungszentrum Juelich GmbHGermany

根据交流约瑟夫森效应,研究了嵌入Fabry-Perot谐振腔里的约瑟夫森结阵列在微波辐照下的相位锁定问题。结阵列是由生长在双晶钇稳定氧化锆(YSZ)基片上的YB2Cu3O7(YBCO)超导薄膜光刻成微桥得到的。通过优化设计,在温度为79.2K辐照频率为77... 详细信息

根据交流约瑟夫森效应,研究了嵌入Fabry-Perot谐振腔里的约瑟夫森结阵列在微波辐照下的相位锁定问题。结阵列是由生长在双晶钇稳定氧化锆(YSZ)基片上的YB2Cu3O7(YBCO)超导薄膜光刻成微桥得到的。通过优化设计,在温度为79.2K辐照频率为77.465GHz的条件下,包含620个串联约瑟夫森双晶结的结阵列在外加微波辐照下实现了相位锁定,得到了陡峭的夏皮罗台阶。其第一级夏皮罗台阶的电压约为0.1V,台阶高度约为0.17mA。试验结果表明,这种结阵列结构在电压基准的应用上有极大的优势,而且这种准光学耦合方法在太赫兹信号发生和检测方面有很好的应用前景。

关键词：高温超导约瑟夫森效应 Fabry-Perot谐振腔约瑟夫森结阵列

Public debate on metallic hydrogen to boost high pressure research

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Matter and Radiation at Extremes 2017年第6期2卷 275-277页

作者： Hua Y.Geng National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsCAEPP.O.Box 919-102MianyangSichuan 621900PR China

Instead of praises from colleagues,the claim of observation of metallic hydrogen at 495 GPa by Dias and Silvera met much skepticism,and grew into a public debate at the International Conference on High-Pressure Science and technology,*** briefly review this debate,and extend the topic to show that this disputation could be an opportunity to benefit the whole high pressure community.

关键词： High pressure Metallic hydrogen Quantum solid and liquid Phase stability superconductivity

Kagome晶格补偿型半金属Ni_(3)In_(2)S_(2)创纪录的高迁移率和极大磁电阻现象

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Science China Materials 2023年第5期66卷 2032-2038页

作者：房红伟吕孟苏豪袁健李一苇徐丽璇刘帅魏立阳刘馨琪杨海峰姚岐王美晓郭艳峰史武军陈宇林刘恩克柳仲楷 School of Physical Science and technology ShanghaiTech UniversityShanghai 201210China University of Chinese Academy of Sciences Beijing 100049China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China Center for Transformative Science ShanghaiTech UniversityShanghai 201210China Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE) ShanghaiTech UniversityShanghai 201210China Department of Physics University of OxfordOxford OX13PUUnited Kingdom

具有Kagome晶格的晶体有很多有趣的性质,包括受挫磁阻、电荷有序、拓扑态、超导和关联现象.为了在电子学和自旋电子学应用中实现高性能Kagome晶格化合物,需要对能带结构仔细调整.本文采用输运测量、角分辨光电子能谱和从头计算等方法研... 详细信息

具有Kagome晶格的晶体有很多有趣的性质,包括受挫磁阻、电荷有序、拓扑态、超导和关联现象.为了在电子学和自旋电子学应用中实现高性能Kagome晶格化合物,需要对能带结构仔细调整.本文采用输运测量、角分辨光电子能谱和从头计算等方法研究了Kagome晶格晶体Ni_(3)In_(2)S_(2)的电子结构.输运测量表明,Ni_(3)In_(2)S_(2)是一种在Kagome晶格材料中具有创纪录的高载流子迁移率(空穴和电子迁移率分别约为8683和7356 cm^(2)V^(-1)S^(-1))和极大磁电阻(在2 K和13 T时为15,518%)的补偿半金属.Ni在Kagome晶格中的3d电子导致的非直接带隙、小的电子/空穴口袋和大的带宽的能带结构特征很好地解释了这些特殊的性质.这项工作表明,晶体场和掺杂是优化Kagome晶格晶体输运特性的关键因素.我们的工作为Kagome晶格半金属在电子学和自旋电子学方面的应用提供了材料基础和优化路径.

关键词： kagome-lattice high mobility extreme magnetoresistance compensated semimetal electronic band structure

Topological electronic states in HfRuP family superconductors

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npj Computational Materials 2019年第1期5卷 88-93页

作者： Yuting Qian Simin Nie Changjiang Yi Lingyuan Kong Chen Fang Tian Qian Hong Ding Youguo Shi Zhijun Wang Hongming Weng Zhong Fang Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Department of Materials Science and Engineering Stanford UniversityStanfordCA 94305USA CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing100190China Songshan Lake Materials Laboratory DongguanGuangdong 523808China

Based on the first-principles calculations and experimental measurements,we report that the hexagonal phase of ternary transition metal pnictides TT’X(T=Zr,Hf;T’=Ru;X=P,As),which are well-known noncentrosymmetric superconductors with relatively high transition temperatures,host nontrivial bulk *** the superconducting phase transition,we find that HfRuP belongs to a Weyl semimetal phase with 12 pairs of type-II Weyl points,while ZrRuAs,ZrRuP and HfRuAs belong to a topological crystalline insulating phase with trivial Fu-Kane Z_(2) indices but nontrivial mirror Chern ***-quality single crystal samples of the noncentrosymmetric superconductors with these two different topological states have been obtained and the superconductivity is verified *** wide-range band structures of ZrRuAs have been identified by ARPES and reproduced by theoretical *** with intrinsic superconductivity,the nontrivial topology of the normal state may generate unconventional superconductivity in both bulk and *** findings could largely inspire the experimental searching for possible topological superconductivity in these compounds.

关键词： nontrivial superconductors topological

superconductivity in zirconium polyhydrides with T_(c) above 70 K

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Science Bulletin 2022年第9期67卷 907-909,M0003页

作者： Changling Zhang Xin He Zhiwen Li Sijia Zhang Shaomin Feng Xiancheng Wang Richeng Yu Changqing Jin Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

Hydrogen is expected to be a metal at sufficient high pressures[1]while it can also be a high temperature superconductor based on BCS theory because of its high Debye temperature arising from the light mass of hydrogen[2].Since it is very challenging to reach the pressure for the hydrogen metallization,the “chemically precompressed” hydrogen-rich compounds were in turn proposed[3,4]to realize high temperature superconductivity at lower *** experimental discovery of high temperature superconductivity[5]in SH3 has greatly stimulated efforts to explore new hydrogen-rich superconductors,such as in rare earth polyhydrides[6,7].

关键词：高温超导超导现象高压高温激光加热金属化临界转变温度极端条件金属氢

Moirésuperlattice modulations in single-unit-cell FeTe films grown on NbSe_(2)single crystals

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Chinese Physics B 2021年第12期30卷 131-135页

作者： Han-Bin Deng Yuan Li Zili Feng Jian-Yu Guan Xin Yu Xiong Huang Rui-Zhe Liu Chang-Jiang Zhu Limin Liu Ying-Kai Sun Xi-Liang Peng Shuai-Shuai Li Xin Du Zheng Wang Rui Wu Jia-Xin Yin You-Guo Shi Han-Qing Mao Beijing National Laboratory for Condensed Matter Physics and institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physics University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Laboratory for Topological Quantum Matter and Spectroscopy(B7) Department of PhysicsPrinceton UniversityPrincetonNJ 08544USA Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Interface can be a fertile ground for exotic quantum states,including topological superconductivity,Majorana mode,fractal quantum Hall effect,unconventional superconductivity,Mott insulator,*** we grow single-unit-cell(1UC)FeTe film on NbSe_(2)single crystal by molecular beam epitaxy(MBE)and investigate the film in-situ with a home-made cryogenic scanning tunneling microscopy(STM)and non-contact atomic force microscopy(AFM)combined *** find different stripe-like superlattice modulations on grown FeTe film with different misorientation angles with respect to NbSe_(2)*** show that these stripe-like superlattice modulations can be understood as moirépattern forming between FeTe film and NbSe_(2)*** results indicate that the interface between Fe Te and NbSe2 is atomically *** STM-AFM combined measurement,we suggest that the moirésuperlattice modulations have an electronic origin when the misorientation angle is relatively small(≤3°)and have structural relaxation when the misorientation angle is relatively large(≥10°).

关键词： scanning tunneling microscopy(STM) atomic force microscopy(AFM) FeTe film moirésuperlattice misorientation