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Heavy fermions in high magnetic fields

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Chinese Physics B 2019年第1期28卷 25-38页

作者： M Smidman B shen C y Guo L Jiao x Lu H Q yuan Center for Correlated Matter and Department of Physics Zhejiang UniversityHangzhou 310058China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–yosida(RKKy) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.

关键词： heavy fermions high magnetic fields quantum phase transitions heavy fermion superconductivity topological Kondo systems

Structure modification and recovery of amorphous Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1 magnetic ribbons after autoclave treatment:SAxS and thermodynamic analysis

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Journal of Materials Science & Technology 2019年第1期35卷 118-126页

作者： L.y.Guo x.Wang K.C.shen K.B.Kim S.Lan x.L.Wang W.M.Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Department of Nanotechnology and Advanced Materials Engineering Sejong University Herbert Gleiter Institute of Nanoscience School of Materials Science and Engineering Nanjing University of Science and Technology Department of Physics City University of Hong Kong

The structure, crystallization kinetics and magnetic property of as-quenched Fe_(73.5)Si_(13.5)B_9Nb_3Cu_1 amorphous ribbon(R0) as well as ribbons after autoclave treatment at 100°C and 150°C(R1 and R2) have been systematically studied by various techniques. With increasing autoclave treatment temperature,the measured structural, kinetic and magnetic parameters of samples increase firstly, i.e. R0 y transforming from fcc to bcc structure during the autoclave treatment and that the autoclave treatment can decrease the large radius(r_M) MRO(medium range order),but increase the small rMMRO. The measured structural, thermal and magnetic parameters of R2 sample have a tendency to recover toward as-quenched R0 sample. The thermal and magnetic parameters of samples after solely annealing treatment at higher temperature have no obvious recover *** uneven actions of pressure and temperature in autoclave treatment may be helpful for us to search a new method to improve the magnetic properties of Fe-based glasses.

关键词： SAxS (small-angle x-ray scattering) Fe-based glass Thermodynamic Magnetic ribbon DSC (differential scanning calorimetry)

3D－QSAR　STUDy　ON　HUPERZINE　A　ANALOGS　WITH　MOLECULAR　MODELING　AND　COMPARATIVE　MOLECULAR　FIELD　ANALySIS（COMFA）　METHODS

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Chinese Chemical Letters 1996年第3期7卷 253-256页

作者： Jiang, HL Chen, Kx Chen, JZ Tang, y Wang, QM Li, Q shen, x Ji, Ry CHINESE ACAD SCI SHANGHAI INST MAT MEDSHANGHAI 200031PEOPLES R CHINA

On the basis of conformational search for ten huperzine A analogs according to the structure ofAChE active site witll our approach BCSPL,we performed a 3D-QSAR analysis for these compounds usingmolecular modeling and CoMFA method. The calculation results can be used to explain the relationshipbetween the structUre properties and the activities.

关键词： QSAR STUDy ON HUPERZINE ANALySIS ANALOGS

MOLECULAR　MECHANICAL　AND　QUANTUM　CHEMICAL　CALCULATION　ON　ACyLATION　REACTIVITy　FOR　1－（NITRO　SUBSTITUTED　ANILINO）－4－SUBSTITUTED－2，6－PIPERAZINEDIONES

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Chinese Chemical Letters 1995年第8期6卷 691-694页

作者： Jiang, HL Li, Q Chen, Kx Tang, y shen, x Ji, Ry xie, yy Chinese Acad Sci Shanghai Inst Mat Med Shanghai 200031 Peoples R China

Molecular mechanical and quantum chemical methods were used to calculate the conformational and electronic structures of the template molecules of (nitro substituted an ill no)-4 - sub st nut ed -2, 6 -piperazinediones, With the calculation results we explained the acylation reactivity of title compounds satisfactorily.

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Microstructure and mechanical optimization of probeless friction stir spot welded joint of an Al-Li alloy

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Journal of Materials Science & Technology 2018年第10期34卷 1739-1746页

作者： Q. Chu W.y. Li x.W. yang J.J. shen A. Vairis W.y. Feng W.B. Wang State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an710072 China Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics Geesthacht 21502 Germany Mechanical Engineering Department TEl of Crete Heraklion Crete 71004 Greece China PSW Center Beijing 100024 China

In this work, a third generation AI-Li alloy has been successfully spot welded with probeless friction stir spot welding （P-FSSW）, which is a variant of conventional friction stir welding. The Box-Behnken exper-imental design in response surface methodology （RSM） was applied to optimize the P-FSSW parameters to attain maximum tensile/shear strength of the spot joints. Results show that an optimal failure load of 7.83 kN was obtained under a dwell time of 7.2 s, rotation speed of 950 rpm and plunge rate of 30 mm/rain. Sufficient dwell time is essential for heat conduction, material flow and expansion of the stir zone to form a sound joint. Two fracture modes were observed, which were significantly affected by hook defect. In addition to mechanical testing, electron backscattering diffraction （EBSD） and differential scanning calorimetry （DSC） were used for microstructure evolution and property analysis. The precipitation of GP zone and AI3Li as well as the ultrafine grains were responsible for the high microhardness in the stir zone.

关键词： Probeless friction stir spot welding Precipitation Mechanical property Fracture mechanism

Monolayer MoS_(2)synaptic devices synergistically modulated by Na^(+)ions and sulfur vacancies for neuromorphic computing and pain perception stimulation

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Journal of Materials Science & Technology 2023年第32期163卷 121-131页

作者： y.B.Liu D.Cai T.C.Zhao M.shen x.Zhou Z.H.Zhang x.W.Meng D.E.Gu State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610066China Laboratory of Controllable Preparation and Application of Nanomaterials Chinese Academy of SciencesBeijing 100190China

Ion based synaptic devices(ISDs)are one of the excellent candidates for neuromorphic ***,most of ISDs utilized additional ion sources to supply ions for adjusting the conductance of the device channel,which might hinder the large-scale integration for fabricating hierarchical artificial neural *** a high-performance monolayer MoS_(2) ISD is demonstrated using Na^(+)ions doped in MoS_(2) lattice as ion *** from the Na^(+)ions and S vacancy defects in the MoS_(2) lattice,the device not only exhibits various synaptic plasticity(long-and short-term plasticity)and typical biological features(pain-perceptual nociceptors and associative learning),but also has a low synaptic event response voltage(100 mV)and a low energy consumption(0.92 pJ)for a synaptic event.A dissociation-adsorptionmigration-binding model is proposed to elaborate the resistance switching mechanism,which is corroborated by density functional theory calculations and *** addition,an artificial neural network(ANN)based on MoS_(2) ISDs is simulated for the recognition of the MNIST handwritten *** deviation of the recognition accuracy is less than 8%compared to the ideal floating-point numeric *** results provide a new strategy for fabricating high-performance ISDs for neuromorphic computing.

关键词： 2D materials Monolayer Molybdenum disulfide Synapses Neuromorphic computing

Bulk nanocrystalline W-Ti alloys with exceptional mechanical properties and thermal stability

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Journal of Materials Science & Technology 2022年第19期114卷 16-28页

作者： H.x.xue x.C.Cai B.R.Sun x.shen C.C.Du x.J.Wang T.T.yang S.W.xin T.D.shen Clean Nano Energy Center State Key Laboratory of Metastable Materials Science and TechnologyYanshan UniversityQinhuangdao 066004China CSSC 723rd Research Institute China State Shipbuilding Corporation LimitedYangzhou 225000China

Nanocrystalline(NC)W metals and alloys often exhibit higher radiation tolerance and strength than their coarse-grained ***,their thermal stability is low,making it difficult to achieve bulk NC W metals and alloys by consolidation using conventional techniques such as pressure-less sintering,hot-explosive-compaction sintering,and spark plasma *** we report the synthesis and mechanical properties of bulk NC W_(100-x)Ti_(x)(x=10 at.%-30 at.%)alloys prepared by consolidating mechanically alloyed NC powders under a high-temperature/high-pressure *** 20 at.%-30 at.%Ti largely improves the sinterability of NC W-Ti alloy *** room-temperature microhardness and compressive yield strength of consolidated bulk NC W_(80)Ti_(20) alloy are∼16.9 and 6.0 GPa,respectively,which are mainly caused by grain boundary strengthening and significantly higher than those of previously reported W and W *** ultimate compressive strength of bulk NC W_(80)Ti_(20) measured between 900 and 1100°C deceases with increasing *** behavior can be explained by the activation of Rachinger grain boundary *** grain growth is observed in bulk NC W_(80)Ti_(20) after compression at 1000°*** calculation suggests that it is the segregation of Ti at grain boundaries that decreases the specific grain boundary free energy and makes the NC W_(80)Ti_(20) alloy thermodynamically stable.

关键词： Nanocrystalline W-Ti alloys Segregation Grain boundary energy Strength Hardness

Research on Characteristics of Density Current Under the Action of Waves

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China Ocean Engineering 1997年第1期12卷 69-78页

作者： Li, DS shen, y Ren, RS Chen, y HOHAI UNIV NANJING 210098PEOPLES R CHINA

In this paper, the characteristics of density current under the action of waves are described with the help of flume experiment and theoretical analysis. The study shows that turbid water under the action of the waves can present three types of motion, i. e. significant stratification, fragile stratification and strong mixing. The motion gf turbid;,ater presents significant stratification when (H/D)/root Delta rho/rho less than or equal to 4.5, generally this state is known as density current. The formulas of motion velocity, thickness, and discharge of density current moving on horizontal bottom are derived by use of basic equations such as momemtum equation, equation of energy conservation and continuity equation of fluid. The time-average velocity and the thickness of density current under the action of waves have a relationship with such parameters as relative density (Delta rho/rho), wave height (H), and water depth (D). When these parameters are determined, the time-average thickness and motion velocity of density current are also determined. The relative thickness of density current (D-t/D) decreases with the increase of Delta rho/rho and increases with the increase of H/D. On the other hand, the motion velocity of density current increases with the increase of Delta rho/rho and decreases with the increase of the relative thickness (D-t/D) of density current. It is shown that the calculated results are in agreement with those of the flume experiment.

关键词： turbid current density current gravity current wave action motion velocity thickness

Studies on the energy transfer system of terbium-norfloxacin chelate and its interaction with serum albumins

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Chinese Journal of Chemistry 1997年第2期15卷 138-143页

作者： xu, y shen, Hx Huang, HG NANKAI UNIV DEPT CHEMTIANJIN 300071PEOPLES R CHINA HEBEI INST TECHNOL DEPT CHEM ENGNTANGSHAN 063009HEBEIPEOPLES R CHINA

The energy absorbed by norfloxacin could be transferred to terbium(III) through chelation of norfloxacin with terbium(III), then the characteristic fluorescence emission could be observed. The interaction of serum albumins with norfloxacin have been investigated in this paper. The results showed that HSA could inhibit the energy transfer between norfloxacin and terbium(III). But, BSA could not. It was shown that the binding properties of norfloxacin to HSA and BSA were totally different.

关键词： norfloxacin terbium(III) energy transfer HSA BSA