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Chinese physics B 2024年第5期33卷 688-694页

作者：赵乾张腾飞何斌李子木张森富于国强王建波刘青芳魏晋武 Key laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Key laboratory of Special Functional Materials and Structural Design Ministry of EducationLanzhou UniversityLanzhou 730000China

Antiferromagnet(AFM)/ferromagnet(FM)heterostructure is a popular system for studying the spin–orbit torque(SOT)of ***,the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field,namely the magnetic moment drag effect,which further influences the characteristic of SOT *** this work,we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance(ST-FMR)method.A full analysis on the AFM/FM systems with exchange bias is performed,and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free *** ST-FMR results can be well fitted by this *** obtained the relative accurate SOT efficiencyξ_(DL)=0.058 for the IrMn *** work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.

关键词： antiferromagnets spin-orbit torque exchange bias spin torque ferromagnetic resonance

Probing phase transition of band topology via radiation topology

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Photonics Research 2024年第6期12卷 1150-1157页

作者： CHANG-YIN JI WENZE LAN PENG FU GANG WANG CHANGZHI GU YELIANG WANG JIAFANG LI YUGUI YAO BAOLI LIU Key laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China School of Integrated Circuits and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China

Topological photonics has received extensive attention from researchers because it provides brand new physical principles to manipulate *** topology is characterized using the Berry phase defined by Bloch *** now,the scheme for experimentally probing the topological phase transition of band topology has always been relatively lacking in topological ***,radiation topology can be aroused by the far-field polarization singularities of Bloch states,which is described by the Stokes *** such two types of topologies are both related to Bloch states on the band structures,it is rather surprising that their development is almost ***,in optical analogs of the quantum spin Hall effects(QSHEs)and Su-Schrieffer-Heeger model,we reveal the correlation between the phase transition of band topology and radiation topology and then demonstrate that the radiation topology can be employed to study the band topological *** experimentally demonstrate such an intriguing phenomenon in optical analogs of *** findings not only provide an insightful understanding of band topology and radiation topology,but also can serve as a route to manipulate light.

关键词： transition. topology topological

Highly selective growth of(6,5)single-walled carbon nanotubes from sigma phase alloy catalyst

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Nano Research 2024年第3期17卷 1999-2003页

作者： Liantao Xin Chen Ma Qianru Wu Shaokang Liu Linhai Li Xiuyun Zhang Liu Qian Maoshuai He Dong Li Fangqian Han Shulan Hao Lihu Feng Yahan Li Huaping Liu Lili Zhang Chang Liu Jin Zhang College of Chemistry and Molecular Engineering Qingdao University of Science and TechnologyQingdao 266042China Shenyang national laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China College of physics Science and Technology Yangzhou UniversityYangzhou 225002China Center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The chirality structure of a single-walled carbon nanotube(SWNT)strongly depends on the composition of catalyst used in the chemical vapor deposition *** this study,we develop a porous magnesia supported manganese-rhenium(MnRe/MgO)catalyst for chirality-selective synthesis of *** characterizations reveal that(6,5)tubes with a selectivity higher than 70%are grown from the Re-rich MnRe/MgO *** comparing the SWNT growth results with those of monometallic Mn or Re,the formation of sigma phase,an intermetallic compound occurring in transition-metal alloy systems,is revealed to be crucial for the dominant synthesis of(6,5)*** work not only extends the application of sigma phase alloy for catalytic synthesis of SWNTs,but also sheds lights on the growth of SWNTs with a high chirality selectivity.

关键词： single-walled carbon nanotubes sigma phase manganese-rhenium catalyst selective growth transition-metal alloy

Prediction of impurity spectrum function by deep learning algorithm

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Chinese physics B 2024年第5期33卷 52-63页

作者：刘婷韩榕生陈亮 School of Mathematics and physics North China Electric Power UniversityBeijing 102206China Institute of condensed matter physics North China Electric Power UniversityBeijing 102206China Hebei Key laboratory of physics and Energy Technology North China Electric Power UniversityBaoding 071003China

By using the numerical renormalization group(NRG)method,we construct a large dataset with about one million spectral functions of the Anderson quantum impurity *** dataset contains the density of states(DOS)of the host material,the strength of Coulomb interaction between on-site electrons(U),and the hybridization between the host material and the impurity site(Γ).The continued DOS and spectral functions are stored with Chebyshev coefficients and wavelet functions,*** this dataset,we build seven different machine learning networks to predict the spectral function from the input data,DOS,U,andΓ.Three different evaluation indexes,mean absolute error(MAE),relative error(RE)and root mean square error(RMSE),are used to analyze the prediction abilities of different network *** analysis shows that,for the two kinds of widely used recurrent neural networks(RNNs),gate recurrent unit(GRU)has better performance than the long short term memory(LSTM)network.A combination of bidirectional GRU(BiGRU)and GRU has the best performance among GRU,BiGRU,LSTM,and *** MAE peak of BiGRU+GRU reaches *** have also tested a one-dimensional convolutional neural network(1DCNN)with 20 hidden layers and a residual neural network(ResNet),we find that the 1DCNN has almost the same performance of the BiGRU+GRU network for the original dataset,while the robustness testing seems to be a little weak than BiGRU+GRU when we test all these models on two other independent *** ResNet has the worst performance among all the seven network *** datasets presented in this paper,including the large data set of the spectral function of Anderson quantum impurity model,are openly available at https://***/10.57760/sciencedb.j00113.00192.

关键词： machine learning Anderson impurity model spectral function

Optimization for epitaxial fabrication of infinite-layer nickelate superconductors

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Frontiers of physics 2024年第3期19卷 61-69页

作者： Minghui Xu Yan Zhao Xiang Ding Huaqian Leng Shu Zhang Jie Gong Haiyan Xiao Xiaotao Zu Huiqian Luo Ke-Jin Zhou Bing Huang Liang Qiao School of physics University of Electronic Science and Technology of ChinaChengdu 610054China beijing Computational Science Research Center Beijing 100193China Diamond Light Source Harwell CampusDidcot OX110DEUnited Kingdom beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials laboratory Dongguan 523808China

The discovery of nickelates superconductor creates exciting opportunities to unconventional superconductivity. However, its synthesis is challenging and only a few groups worldwide can obtain samples with zero-resistance. This problem becomes the major barrier for this field. From plume dynamics perspective, we found the synthesis of superconducting nickelates is a complex process and the challenge is twofold, i.e., how to stabilize an ideal infinite-layer structure Nd_(0.8)Sr_(0.2)NiO_(2), and then how to make Nd_(0.8)Sr_(0.2)NiO_(2) superconducting? The competition between perovskite Nd_(0.8)Sr_(0.2)NiO_(3) and Ruddlesden−Popper defect phase is crucial for obtaining infinite-layer structure. Due to inequivalent angular distributions of condensate during laser ablation, the laser energy density is critical to obtain phase-pure Nd_(0.8)Sr_(0.2)NiO_(3). However, for obtaining superconductivity, both laser energy density and substrate temperature are very important. We also demonstrate the superconducting Nd_(0.8)Sr_(0.2)NiO_(2) epitaxial film is very stable in ambient conditions up to 512 days. Our results provide important insights for fabrication of superconducting infinite-layer nickelates towards future device applications.

关键词： nickelate superconductivity infinite-layer plasma condensate plume dynamics

Evolution of Superconducting-Transition Temperature with Superfluid Density and Conductivity in Pressurized Cuprate Superconductors

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Chinese physics Letters 2024年第4期41卷 110-117页

作者：赵金瑜蔡树陈逸雯顾根大闫宏涛郭静韩金宇王鹏玉周亚洲李延春李晓东任治安吴奇周兴江丁阳向涛毛河光孙力玲 Institute of physics Chinese Academy of SciencesBeijing 100190China Center for High Pressure Science&Technology Advanced Research Beijing 100094China condensed matter physics&Materials Science Department Brookhaven National LaboratoryNY 11973-5000USA University of Chinese Academy of Sciences Beijing 100190China Institute of High Energy physics Chinese Academy of ScienceBeijing 100049China beijing Academy of Quantum Information Sciences Beijing 100193China

What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense *** the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal ***,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure *** this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'*** highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.

关键词： superconductors Transition Conductivity

Design, performance and application of a line-imaging velocity interferometer system for any reflector coupled with a streaked optical pyrometer system at the Shenguang-Ⅱ upgrade laser facility

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High Power Laser Science and Engineering 2024年第1期12卷 52-59页

作者： Dawei Yuan Shaojun Wang Huigang Wei Haochen Gu Yu Dai Jiayong Zhong Yutong Li Gang Zhao Jie Zhang Key laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijingChina Institute of Frontiers in Astronomy and Astrophysics of beijing Normal University BeijingChina beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijingChina Key laboratory for Laser Plasmas(MOE)and School of physics and Astronomy Shanghai Jiao Tong UniversityShanghaiChina Department of Astronomy Beijing Normal UniversityBeijingChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina School of Physical Sciences University of Chinese Academy of SciencesBeijingChina Songshan Lake Materials laboratory DongguanChina

The velocity interferometer system for any reflector(VISAR) coupled with a streaked optical pyrometer(SOP) system is used as a diagnostic tool in inertial confinement fusion(ICF) experiments involving equations of state and shock *** validate the process of adiabatically compressing the fuel shell through precise tuning of shocks in experimental campaigns for the double-cone ignition(DCI) scheme of ICF, a compact line-imaging VISAR with an SOP system is designed and implemented at the Shenguang-II upgrade laser facility. The temporal and spatial resolutions of the system are better than 30 ps and 7 μm, respectively. An illumination lens is used to adjust the lighting spot size matching with the target size. A polarization beam splitter and λ/4 waveplate are used to increase the transmission efficiency of our system. The VISAR and SOP work at 660 and 450 nm, respectively, to differentiate the signals from the scattered lights of the drive lasers. The VISAR can measure the shock velocity. At the same time, the SOP system can give the shock timing and relative strength. This system has been used in different DCI campaigns, where the generation and propagation processes of multi-shock are carefully diagnosed.

关键词： double-cone ignition streaked optical pyrometer velocity interferometer system for any reflector

Negative magnetoresistance in the antiferromagnetic semimetal V_(1/3)TaS_(2)

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Chinese physics B 2024年第3期33卷 567-571页

作者：王子彭馨张胜男苏亚慧赖少东周旋吴春翔周霆宇王杭栋杨金虎陈斌翟会飞吴泉生杜建华焦志伟方明虎 Department of physics China Jiliang UniversityHangzhou 310018China beijing national laboratory for condensed matter physics and Institute of physics Chinese Academy of SciencesBeijing 100190China Department of physics Zhejiang UniversityHangzhou 310027China Department of physics Hangzhou Normal UniversityHangzhou 310036China University of Chinese Academy of Sciences Beijing 100049China Collaborative Innovation Center of Advanced Microstructure Nanjing 210093China

Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential *** this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport *** measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band *** was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.

关键词： magnetoresistance antiferromagnetic semimetal band structure

Single crystal growth and transport properties of narrow-bandgap semiconductor RhP_(2)

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Chinese physics B 2024年第8期33卷 545-549页

作者：吴德胜郑萍雒建林 beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials laboratory Dongguan 523808China Quantum Science Center of Guangdong–Hong Kong–Macao Greater Bay Area(Guangdong) Shenzhen 518045China

We report the growth of high-quality single crystals of RhP_(2),and systematically study its structure and physical properties by transport,magnetism,and heat capacity ***-crystal x-ray diffraction reveals that RhP_(2) adopts a monoclinic structure with the cell parameters a=5.7347(10)A,b=5.7804(11)A,and c=5.8222(11)A,space group P2_(1)/c(No.14).The electrical resistivityρ(T)measurements indicate that RhP_(2) exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions,*** temperaturedependent Hall effect measurements show electron domain transport behavior with a low charge carrier *** find that RhP_(2) has a high mobilityμ_(e)~210 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_(e)~3.3×10^(18)cm^(3) at 300 K with a narrow-bandgap *** high mobilityμ_(e) reaches the maximum of approximately 340 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_^(e)~2×10^(18)cm^(-3)at 100 *** magnetic phase transitions are observed from the susceptibilityχ(T)and specific heat C_(p)(T)measurements of RhP_(2).Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.

关键词： single crystal growth narrow band system electrical transport high mobilities

Classification of high-ordered topological nodes towards Moiré flat bands in twisted bilayers

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Science China(physics,Mechanics & Astronomy) 2024年第9期Mechanics & Astronomy) .卷 137-151页

作者： Fan Cui Congcong Le Qiang Zhang Xianxin Wu Jiangping Hu Ching-Kai Chiu beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences RIKEN Interdisciplinary Theoretical and Mathematical Sciences(iTHEMS) CAS Key laboratory of Theoretical physics Institute of Theoretical PhysicsChinese Academy of Sciences Kavli Institute of Theoretical Sciences University of Chinese Academy of Sciences New Cornerstone Science laboratory

At magic twisted angles, Dirac cones in twisted bilayer graphene(TBG) can evolve into flat bands, serving as a critical playground for the study of strongly correlated physics. When chiral symmetry is introduced, rigorous mathematical proof confirms that the flat bands are locked at zero energy in the entire Moiré Brillouin zone(BZ). Yet, TBG is not the sole platform that exhibits this absolute band flatness. Central to this flatness phenomenon are topological nodes and their specific locations in the BZ. In this study, considering twisted bilayer systems that preserve chiral symmetry, we classify various ordered topological nodes in base layers and all possible node locations across different BZs. Specifically, we constrain the node locations to rotational centers,such as Γ and M points, to ensure the interlayer coupling retains equal strength in all directions. Using this classification as a foundation, we systematically identify the conditions under which Moiré flat bands emerge. Additionally, through the extension of holomorphic functions, we provide proof that flat bands are locked at zero energy, shedding light on the origin of the band flatness. Remarkably, beyond Dirac cones, numerous twisted bilayer nodal platforms can host flat bands with a degeneracy number of more than two, such as four-fold, six-fold, and eight-fold. This multiplicity of degeneracy in flat bands might unveil more complex and enriched correlation physics.

关键词： twisted bilayer systems high-ordered topological nodes Morié flat bands high degeneracy

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