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Magnetocaloric effect and slow magnetic relaxation behavior in binuclear rare earth based RE_(2)(L)_(2)(DMF)4(RE=Gd,Tb,and Dy) complexes

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Journal of Rare Earths 2022年第6期40卷 916-923,I0003页

作者： Zhenqian Zhang Yuwei Wu Haifeng Wang Lingwei Li Key Laboratory of Novel materials for Sensor of Zhejiang Province Institute of Advanced Magnetic MaterialsHangzhou Dianzi UniversityHangzhou 310012China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China Key Laboratory of Electromagnetic Processing of materials(Ministry of Education) Northeastern UniversityShenyang 110819China

Three binuclear rare earth based complexes combining RE ions with semirigid tricarboxylic ligand(H_(3)L).namely,[RE_(2)(L)_(2)(DMF)_(4)][RE=Gd,Tb,and Dy;H_(3)L=5-((4-Carboxybenzyl)oxy)isophthalic acid;DMF=N,N-dimethylformamide]complexes,were fabricated success *** RE_(2)(L)_(2)(DMF)_(4) co mplexe s consist of two central RE ions with the same coordination environment which were connected by two tridentate bridging carboxylic groups and two syn-syn bidentate bridging carboxylic groups originating from the L^(3-)ligands to form the{RE_(2)}dimeric unit,and thus provides the basis for further constructing a dense three-dimensional(3 D)network ***,the present RE_(2)(L)_(2)(DMF)_(4) complexes can be described by a topology diagram with the topology point symbol of{4^(2)·6}_(2){4^(4)·6^(2)·8^(7)·10^(2)}.Weak antiferromagnetic(AFM)coupling between the adjacent RE ions for all the present complexes was found according to the magnetic *** observed significant cryogenic magnetocaloric effect(MCE)with the maximum magnetic entropy change-ΔS_(M)^(max) to be 26.3 J/(kg·K)withΔH=7 T in Gd_(2)(L)_(2)(DMF)_(4) complex makes it competitive for the cryogenic magnetic ***,the slow magnetic relaxation behavior at 0.2 T dc field with an obvious large U_(eff)/k=45(4)K and τ_(0)=6.5(2)×10^(-10)s was confirmed in Dy_(2)(L)_(2)(DMF)_(4)*** work not only provides an effective strategy for obtaining molecular materials with high MCE,but also confirms that tricarboxylate ligands are the ideal choice for constructing stable high dimensional geometric structures.

关键词： Magnetocaloric effect Rare earth based complex magnetic properties Slow magnetic relaxation bahavior

Phase structure evolution and its effect on magnetic and mechanical properties of B-doped Sm_(2)Co_(17)-type magnets with high Fe content

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Chinese Physics B 2024年第9期33卷 582-588页

作者： Yao-Wen Li Zhuang Liu Hai-Chen Wu Fang Wang Chao-Qun Zhu Dong-Liang Tan Yu Liu Yang Yang Ming-Xiao Zhang Ren-Jie Chen A-Ru Yan Key Laboratory of magnetic Molecules and magnetic Information materials of Ministry ofEducation&School of Chemistry and materials Science Shanxi Normal UniversityTaiyuan 030032China CISRI&NIMTE Joint Innovation center for Rare Earth Permanent Magnets Ningbo Institute ofMaterial Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China

The unique cellular microstructure of Fe-rich Sm_(2)Co_(17)-type permanent magnets is closely associated with the structure of the solid solution *** investigate the phase structure,magnetic properties,and mechanical behavior of B-doped Sm_(2)Co_(17)-type magnets with high Fe *** doped B atoms can diffuse into the interstitial vacancy,resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in ***,the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2:17R phases in the solid solution stage,which inhibits the ordering transformation of 1:7H phase during aging and affects the generation of the cellular structure,and to result in a decrease in magnetic properties,yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical ***,the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm_(2)Co_(17)-type *** study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm_(2)Co_(17)-type magnets with high Fe content.

关键词： Sm_(2)Co_(17)-type magnets magnetic and mechanical properties

Nanocavity-Mediated Fast magnetic Vortex Core In-Situ Switching by Local magnetic Field

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Chinese Physics Letters 2021年第12期38卷 76-79页

作者： Xiao-Ping Ma Hongguo Yang Changfeng Li Cheng Song Hong-Guang Piao Hubei Engineering Research center of Weak magnetic-Field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Key Laboratory of Advanced materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Fast in situ switching of magnetic vortex core in a ferromagnetic nanodisk assisted by a nanocavity,with diameter comparable to the dimension of a vortex core,is systematically investigated by changing the strength as well as the diameter of the effective circular region of the applied magnetic *** applying a local magnetic field within a small area at the nanodisk center,fast switching time of about 35 ps is achieved with relatively low field strength(70 mT)which is beneficial for fast data reading and *** reason for this phenomenon is that the magnetic spins around the nanocavity is aligned along the cavity wall due to the shape anisotropy when the perpendicular field is applied,which deepens the dip around the vortex core,and thus facilitates the vortex core switching.

关键词： strength cavity vortex

Unconventional room-temperature negative magnetoresistance effect in Au/n-Ge:Sb/Au devices

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Chinese Physics B 2024年第3期33卷 602-608页

作者：何雄杨凡黎牛浩峪王立峰易立志许云丽刘敏潘礼庆夏正才 Hubei Engineering Research center of Weak magnetic-field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Wuhan National High magnetic Field center Huazhong University of Science and TechnologyWuhan 430074China

Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room ***,how to obtain a large room-temperature negative MR effect in them remains to be *** this paper,by designing an Au/n-Ge:Sb/Au device with metal electrodes located on identical side,we observe an obvious room-temperature negative MR effect in a specific 50 T pulsed high magnetic field direction environment,but not in a static low magnetic field *** the analysis of the experimental measurement of the Hall effect results and bipolar transport theory,we propose that this unconventional negative MR effect is mainly related to the charge accumulation on the surface of the device under the modulation of the stronger Lorentz force provided by the pulsed high magnetic *** theoretical analytical model is further confirmed by regulating the geometry size of the *** work sheds light on the development of novel magnetic sensing,magnetic logic and other devices based on non-magnetic semiconductors operating in pulsed high magnetic field environment.

关键词： magnetoresistance germanium-based devices pulsed high magnetic fields

Dynamical anisotropic magnetoelectric effects at ferroelectric/ferromagnetic insulator interfaces

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Chinese Physics B 2019年第9期28卷 57-61页

作者： Yaojin Li Chenglong Jia Key Laboratory for Magnetism and magnetic materials of Ministry of Education Lanzhou UniversityLanzhou 730000China Electronic materials Research Laboratory International center for Dielectric Research Xi’an Jiaotong UniversityXi’an 710049China Institute of materials Research Slovak Academy of Sciences Watsonova 4704001 KosiceSlovakia

The interfacial magnetoelectric interaction originating from multi-orbital hopping processes with ferroelectricassociated vector potential is theoretically investigated for complex-oxide composite *** mismatch in the electrical permittivity of the ferroelectric and ferromagnetic materials gives rise to giant anisotropic magnetoelectric effects at their *** study reveals a strong linear dynamic magnetoelectric coupling which genuinely results in electric control of magnetic *** constitutive conditions for negative refractive index of multiferroic composites are determined by the analysis of light propagation.

关键词： interfacial magnetoelectric effect ferromagnetic insulator magnetic susceptibility refractive index

Numerical analysis of high Mach flow and flow reversal in the experimental advanced superconducting tokamak divertor

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Chinese Physics B 2011年第9期20卷 276-281页

作者：欧靖杨锦宏 Institute of Plasma Physics Chinese Academy of Sciences center for magnetic Fusion Theory Chinese Academy of Sciences

The B2-Eirene （SOLPS 4.0） code package is used to investigate the plasma parallel flow, i.e., the scrape-off layer （SOL） flow, in the experimental advanced superconducting tokamak （EAST） divertor. Simulation results show that the SOL flow in the divertor region can exhibit complex behaviour, such as a high Mach flow and flow reversal in different plasma regimes. When the divertor plasma is in the detachment state, the high Mach flow with approaching or exceeding sonic speed is observed away from the target plate in our simulation. When the divertor plasma is in the high recycling ~tate, the flow reversM with a ~mall Mach number （IMI 〈 0.2） is observed near the X-point along the separatrix region. The driving mechanisms for the high Mach flow and the reversed flow are analysed theoretically through momentum and continuity equations, respectively. The profile of the ionization sources is shown to be a possible formation condition causing the complex behaviour of the SOL flow. In addition, the effects of the high Mach flow and the flow reversal on the impurity transport are also discussed in this paper.

关键词： hiuh Mach flow flow reversal ionization source divertor I)lasma

Switching Behavior Induced by Electric and magnetic Fields in （La0.73Bi0.27）0.67Ca0.33MnO3

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Chinese Physics Letters 2014年第4期31卷 159-162页

作者： WANG Ye-Shuai XIA Nian-Ming ZUO Hua-Kun SHEN Yi-Ning XIA Zheng-Cai Wuhan National High magnetic Field center Huazhong University of Science and Technology Wuhan 430074

Both electric and magnetic field-induced switching behaviors between a high resistive state and a low resistive one are observed in （La0.73Bi0.27）0.67Ca0.33MnO3. The effects of magnetoresistance *** electric-resistance suggest that the applied electric field and magnetic field greatly tune the percolative paths in the phase-separated system. According to the experimental results, the switching behaviors may come from the coexistence of the charge ordering state, and localized and freedom ferromagnetic states, in which the external field destroys partially the localized ferromagnetic states and charge ordering leads to the ferromagnetic state growth, which causes a switch between a high resistive state and low resistive one. This makes the doped manganite a good system for both electric and magnetic field sensor materials.

关键词： SWITCHING circuits magnetic fields ELECTRIC resistance FERROMAGNETISM MAGNETORESISTANCE

Electron modulation of cobalt carbonate hydroxide by Mo doping for urea-assisted hydrogen production

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Journal of Energy Chemistry 2022年第7期31卷 258-265,I0007页

作者： Siyu Zheng Hongye Qin Xuejie Cao Tongzhou Wang Wenbo Lu Lifang Jiao Key Laboratory of Advanced Energy materials Chemistry(Ministry of Education) Renewable Energy Conversion and Storage Center(Re Cast)College of ChemistryNankai UniversityTianjin 300071China Key Laboratory of magnetic Molecules and magnetic Information materials(Ministry of Education) School of Chemistry and Material ScienceShanxi Normal UniversityTaiyuan 030035ShanxiChina Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Combining urea oxidation reaction(UOR) with hydrogen evolution reaction(HER) is an effective method for energy saving and highly efficient electrocatalytic hydrogen production. Herein, molybdenumincorporated cobalt carbonate hydroxide nanoarrays(CoxMoyCH) are designed and synthesized as a bifunctional catalyst towards UOR and HER. Benefiting from the Mo doping, the dispersed nanoarray structure and redistributed electron density, the CoxMoyCH catalyst display outstanding catalytic performance and durability for both HER and UOR, affording the overpotential of 82 m V for HER and delivering a low potential of the 1.33 V for UOR(vs. reversible hydrogen electrode, RHE) to attain a current density of 10 m A cm^(-2), respectively. Remarkably, when CoxMoyCH was applied as bifunctional catalyst in a twoelectrode electrolyzer, a working voltage of 1.40 V is needed in urea-assisted water electrolysis at10 m A cm^(-2) and without apparent decline for 40 h, outperforming the working voltage of 1.51 V in conventional water electrolysis.

关键词： Urea-assisted water electrolysis Bifunctional catalyst Molybdenum doping Cobalt carbonate hydroxides Hydrogen evolution reaction

Study on Cavity Modes for D(H) Ion Cycloton Range Frequency Heating Scenarios in EAST

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Plasma Science and Technology 2010年第6期12卷 651-656页

作者：杨程朱思铮 Institute of Plasma Physics Chinese Academy of Sciences center for magnetic Fusion Theory Chinese Academy of Sciences

For low single-pass absorption of ion cyclotron range frequency （ICRF） wave in the EAST plasma cavity modes are expected to be excited between the low field side （LFS） antenna and the hybrid cut-off layer. The toroidal spectrum for D（H） minority heating scenarios in EAST is modeled by using FELICE （finite elements ion cyclotron emulator）, a full wave code based on plane-stratified geometry. The excitation of cavity modes is studied. The methods for suppressing cavity modes are also discussed, to increase the efficiency of minority ion heating.

关键词： cavity modes ICRF toroidal spectrum FELICE