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Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators

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National Science Review 2024年第2期11卷 15-23页

作者： Rui Chen Hai-Peng Sun Mingqiang Gu Chun-Bo Hua Qihang Liu Hai-Zhou Lu X.C.Xie Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) International Quantum academy Institute for Theoretical Physics and Astrophysics University of Würzburg School of Electronic and Information Engineering Hubei University of Science and Technology Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering International Center for Quantum Materials School of PhysicsPeking University Collaborative Innovation Center of Quantum Matter CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences

The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.

关键词： layerHall effect hidden Berry curvature antiferromagnetic insulator axion insulator, quantum transport

ESTIMATING MULTI-COUNTRY PROSPERITY INDEX: A TWO-DIMENSIONAL SINGULAR SPECTRUM ANALYSIS APPROACH

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Journal of Systems Science & Complexity 2014年第1期27卷 56-74页

作者： ZHANG Jiawei HASSANI Hossein XIE Haibin ZHANG Xun (Corresponding author) Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190 China. The Business School Bournemouth University 89 Holdenhurst Road BH88EB UK. Research Center of Applied Finance University of International Business and Economics Beijing 100029China. Institute oJ Systems Science Academy of Mathematics and Systems Science Chtnese Academy oJ SczencesBeijin9 100190 China.

With the development of the global economy, interaction among different economic entities from one region is intensifying, which makes it significant to consider such interaction when constructing composite index for each country from one region. Recent advances in signal extraction and time series analysis have made such consideration feasible and practical. Singular spectrum analysis （SSA） is a well-developed technique for time series analysis and proven to be a powerful tool for signal extraction. The present study aims to introduce the usage of the SSA technique for multi-country business cycle analysis. The multivariate SSA （MSSA） is employed to construct a model-based composite index and the two dimensional SSA （2D-SSA） is employed to establish the multi-country composite index. Empirical results performed on chinese economy demonstrate the accuracy and stability of MSSA-based composite index, and the 2D-SSA based composite indices for Asian countries confirm the efficiency of the technique in capturing the interaction among different countries.

关键词： 2D-SSA business cycle analysis multi-country composite index singular spectrum anal-ysis.

Effects of heavy metal pollution of highway origin on soil nematode guilds in North Shenyang, China

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Journal of Environmental sciences 2009年第2期21卷 193-198页

作者： HAN Dechang ZHANG Xiaoke TOMAR Vijay Vikram Singh LI Qi WEN Dazhong LIANG Wenju Key Laboratory of Terrestrial Ecological Process Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China Biodiversity Research Laboratory Aligarh Muslim University Aligarh 202002 India Graduate University of the chinese academy of sciences Beijing 100049 China

Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on soil nematode guilds. The contents of soil Pb, Cu, Zn, and the nematode community structure were analyzed. The results showed that the contents of total and available Pb, Ca, Zn varied significantly with the different distances from the highway. Pb was the main pollutant in the soils in the vicinity of Shen-Ha Highway. The zone from 20 to 40 m away from the highway was the most polluted area. The highest abundance of soil nematodes was found at 5 m while the lowest at 20 m away from the highway. Thirty six genera of nematodes belonging to 23 families were identified. Nematode guilds having different responses to soil heavy metals were classified into four types. Soil nematode guilds may act as a prominent indicator to heavy metal pollution of highway origin.

关键词： soil pollution of highway origin heavy metals soil nematode guilds

Validity of the Bouchet's complementary relationship at 102 observatories across China

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Science China Earth sciences 2009年第5期52卷 708-713页

作者： YU JingJie1,2,ZHANG YongQiang3,LIU ChangMing1,2 1 Institute of Geographic sciences and Natural Resources Research,chinese academy of sciences,Beijing 100101,China 2 Key Laboratory of Water Cycle and Related Land Surface Processes,chinese academy of sciences,Beijing 100101,China 3 CSIRO Land and Water,PO Box 1666,Canberra ACT 2601,Australia Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Key Laboratory of Water Cycle and Related Land Surface Processes Chinese Academy of Sciences Beijing China CSIRO Land and Water Canberra Australia

Bouchet in 1963 hypothesized that for large homogeneous land surface with minimum advection of heat and moisture,there exists a 1:1 complementary relationship of potential and actual evaporation coupled through land-atmosphere *** complementary relationship has been widely used to estimate regional actual evaporation and explain the pan evaporation *** examine the standardized potential evaporation(potential evaporation divided by wet environment evaporation) at 102 observatories at different elevations across ***,the relationship is appropriate at the low elevations(<1000 m).With the increase of elevation,vapor transfer power becomes much less than radiation energy budget because of lower vapor pressure deficit and stronger global solar *** a result,at the high elevations(over 1000 m),the excess energy resulted by limited moisture availability is not enough to be converted into drying power of the *** result suggests that the complementary relationship is asymmetric at the high elevations.

关键词： evaporation complementary relationship elevation China

Fabrication of suspended graphene devices and their electronic properties

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chinese Physics B 2010年第9期19卷 12-15页

作者：李强程增光李忠军王志华方英 State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology National Center for Nanoscience and Technology

Suspended graphene devices are successfully fabricated by using a novel PMMA/MMA/PMMA tri-layer resist technique. The gap between graphene and dielectric substrate can be easily controlled by the thickness of the bottom PMMA layer, and no wet-etching with hazardous hydrofluoric acid is involved in our fabrication process. Electrical characterizations on suspended graphene devices are performed in vacuum when in-situ current annealing directly leads to a significant improvement on transport properties of graphene, i.e., the increase of carrier mobility with the reduction of width of Dirac peak. Our results make a new opportunity to study intrinsic properties of graphene.

关键词： graphene transport suspension high mobility

Insights into the characteristics of corrosion products formed on the contact and exposed regions of C1045 steel bolt and nut fasteners exposed to aqueous chloride environments

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Journal of Materials Science & Technology 2023年第4期135卷 250-264页

作者： Enobong Felix Daniel Chao Li Changgang Wang Junhua Dong Inime Ime Udoh Peter Chukwuemeka Okafor Dongjiu Zhang Wenan Zhong Sheng Zhong School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China Corrosion and Electrochemistry unit Department of Pure and Applied ChemistryUniversity of CalabarP.M.B 1115 CalabarCross River StateNigeria Key Laboratory of Space Launching Site Reliability Xichang Satellite Launch CenterHainan Haikou 571126China

This study investigated the characteristics of corrosion products formed on the contact and exposed re-gions of C1045 steel bolt and nut fasteners exposed to aqueous chloride *** corroded sur-face morphology,rust compositions,and corrosion kinetics of the bolt specimen were studied by visual observation,optical microscopy(OM),scanning electron microscopy(SEM),X-Ray diffractometry(XRD),micro-Raman,electron probe micro-analyser(EPMA),and potentiodynamic polarization ***-sults obtained showed a variation in corrosion kinetics,morphology,and composition of the rust layer which were driven by differential aeration and concentration *** to the availability of sufficient dissolved oxygen,the oxyhydroxide compound,lepidocrocite(γ-FeOOH)was detected in the outer rust layer in the exposed region,whereas the inner rust layer was composed of magnetite(Fe_(3)O_(4)).How-ever,the oxygen-deficient contact surface revealed the presence of akaganeite(β-FeOOH)and magnetite(Fe_(3)O_(4))as dominant oxide *** most stable phase,goethite(α-FeOOH)was also detected in the rust formed in both regions,though in significantly low ***,owing to variation in environmental conditions,the amount and density of the rust layer varied in the different *** estimated corrosion stability values for the different regions revealed that the corrosion products formed on the steel surfaces were non-protective,suggesting the need for specific surface treatment as a protec-tive measure.

关键词： Carbon steel Bolt-nut fastener Raman SEM-EDS XRD Rust characterization

STABILITY OF N-DIMENSIONAL LINEAR SYSTEMS WITH MULTIPLE DELAYS AND APPLICATION TO SYNCHRONIZATION

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Journal of Systems Science & Complexity 2006年第2期19卷 149-156页

作者： Weihua DENG Jinhu LU Changpin LI School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China Department of Mathematics Shanghai University Shanghai 200444 China. Key Laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Department of Ecology and Evolutionary Biology Princeton University NJ 08544 USA

This paper further investigates the stability of the n-dimensional linear systems with multiple delays. Using Laplace transform, we introduce a definition of characteristic equation for the n-dimensional linear systems with multiple delays. Moreover, one sufficient condition is attained for the Lyapunov globally asymptotical stability of the general multi-delay linear systems. In particular, our result shows that some uncommensurate linear delays systems have the similar stability criterion as that of the commensurate linear delays systems. This result also generalizes that of Chen and Moore （2002）. Finally, this theorem is applied to chaos synchronization of the multi-delay coupled Chua＇s systems.

关键词： Chaos synchronization multi-delay linear systems stability.

An in situ high-pressure X-ray diffraction experiment on hydroxyapophyllite

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chinese Physics B 2013年第1期22卷 167-170页

作者：范大伟魏舒怡谢鸿森 Institute of Geochemistry of Laboratory for High Temperature & High Pressure Study of the Earth's Interior Chinese Academy of Sciences

The compression behavior of a natural hydroxyapophyllite is investigated up to about 10.01 GPa at 300 K using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at the High Pressure Experiment Station, Beijing Synchrotron Radiation Facility （BSRF）. Over this pressure range, no phase change or disproportionation is observed. The isothermal equation of state is determined for the first time. The values of zero-pressure volume V0, isothermal bulk modulus K0, and K0＇ refined with a third-order Birch-Mumaghan equation of state are V0 = 1276.3 ± 0.9 A3, K0 = 71± 3 GPa, and K0＇ = 8 ±1. Furthermore, we confirm that the values of linear compressibility β along the a and c directions of hydroxyapophyllite are elastically anisotropic.

关键词： hydroxyapophyllite X-ray diffraction equation of state high pressure

Speciation study of chromium corrosion product in molten LiF-NaF-KF salt

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Nuclear Science and Techniques 2015年第6期26卷 125-128页

作者：邱杰邹杨俞国军何上明刘文冠贾彦彦李志军徐洪杰 Shanghai Institute of Applied Physics Chinese Academy of Sciences University of chinese academy of sciences

To investigate the corrosion products of Cr in molten FLi Na K salt(46.5 mol% Li F–11.5 mol% Na F–42mol% KF), the corrosion test of the pure metal Cr was performed in molten FLi Na K salt at 700?C for 200 *** FLi Na K salt after the corrosion test was thoroughly investigated by X-ray absorption near-edge structure spectroscopy, a transmission electron microscope, and X-ray diffraction. The results demonstrate that the predominant oxidation state of Cr in FLi Na K salt is Cr^(3+), and the main corrosion product in cooled FLi Na K salt is K_2NaCrF_6.

关键词：腐蚀产物金属铬钾盐熔融 X射线吸收近边结构透射电子显微镜形态腐蚀试验