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Observation of magnetic domain Structures of magnetic Thin Films by the Lorentz Electron Microscopy

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 119-124页

作者： A. Okada M Chimura K Hamada M Arita I. Ishida(Advanced Materials Science Laboratory, Division of Electronics and information Engineering, Graduate School of Engineering, Hokkaido University,Sapporo 060-8628, Japan) Division of Electronics and Information Engineering Graduate School of Engineering Hokkaido University Sapporo 060-8628 Japan

The microstructure change in thin NiFe/Cu/NiFe films during the magnetization process was observed by the Lorentz electronmicroscopy. TWo types of films were prepared: (1) one NiFe layer with anisotropy and the other layer without, and (2) both NiFe layershave anisotropy normal each other. The domain wall migration and magnetization rotation processes in each of NiFe layers could be observed separately. The presence of magnetic anisotropy in the magnetic layer effectively controls the behavior of magnetic domains. Theinteraction between the two NiFe layers of the film could be observed not so strong in the present experiment.

关键词： magnetic domain domain wall Lorentz microscopy multi-layers thin films hysteresis loop permalloy film

Characteristics of magnetic domain deflection of Tb_(0.3)Dy_(0.7)Fe_2 alloy

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Journal of Rare Earths 2016年第9期34卷 882-888页

作者：喻曹丰王传礼邓海顺何涛钟长鸣 College of Mechanical Engineering Anhui University of Science and Technology

In order to expand the applications of giant magnetostrictive materials in the field of precision positioning, an extreme value model of free energy was established with deflection angle of magnetic domain as the independent variable from the micro-scopic aspect. The model was based on Stoner-Wohlfarth （S-W） model wherein Tb0.3Dy0.7Fe2 alloy was taken as a research object, and the deflection law of magnetization angle of single magnetic domain was studied through drawing the equipotential curves and changing curves of free energy function under different applied stresses and in different magnetic fields. Research results showed that there were three kinds of magnetization angles of single magnetic domain as for Tb0.3Dy0.7Fe2 alloy, namely 35.26o , 90o and 144.74o ; under the action of applied stresses, the magnetization anglesθwere deflected to the direction of 90o for the magnetic domains of 35.26o and 144.74o and the magnetization anglesψ were changed and transited to the direction ofψ=135o for the magnetic domain of 90o ; the magnetic domain was deflected under the action of small magnetic field for magnetic domain of 35.26o ; with the increase of magnetic field intensity, the magnetic domain of 90o had a transition trend to a stationary planar ofψ=ψ0; the magnetic domain of 144.74o had a transition trend to the direction of magnetic domain of 35.26o. These results laid a foundation for the magnetostrictive mechanism and establishment of precision positioning theories of the giant magnetostrictive materials.

关键词： Tb0.3Dy0,7Fe2 alloy magnetic domain magnetization angle Stoner-Wohlfarth model rare earths

Microstructure,magnetic domain and dynamic loss of surface-textured Fe-based nanocrystalline alloy

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Journal of Materials Science & Technology 2022年第25期120卷 1-7页

作者： Aina He Jiawei Li Mingkun Wang Anding Wang Yao Xiao Yaqiang Dong Hai Guo Rongrong Jiang Weixing Xia Lihong Dong Haidou Wang Jianya Ge CAS Key Laboratory of magnetic Materials and Devices Zhejiang Province Key Laboratory of Magnetic Materials and Application TechnologyNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China Ningbo Zhongke B Plus New Materials Technology Co. LtdNingbo 315201China National Key Lab for Remanufacturing Army Academy of Armored ForcesBeijing 100072China Jinhua Polytechnic Jinhua 321007China

Heterogeneous coarse surface crystallites induced in the industrial Fe-rich nanocrystalline alloy is an obstacle for high-frequency and high-power commercial ***,the phase,crystal orientation,nanostructure and magnetic domain evolution of the surface-crystallized Fe-rich alloy were systematically *** and inverse pole figures analysis confirms that the DOordered dendriticcrystallites bear-oriented fiber texture before and after annealing at the free surface,while ultrafine nanocrystals are randomly oriented in the interior and wheel surface after *** compared to zero magnetic-field-annealing,the transverse magnetic-field-annealing induces weakly oriented fiber texture and relatively uniform dendritic-crystallites at the surface,and uniform anisotropy in the interior and surface,which promotes smooth wall motion at the surface and magnetization rotation in the *** synergetic effect reduces the excess loss and leads reduction in dynamic loss at 1.0 T and10 kHz by 36%.

关键词： Nanocrystalline alloy Crystallization Texture magnetic domain Dynamic loss

Ballistic current induced effective force on magnetic domain wall

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Nano-Micro Letters 2009年第1期1卷 34-39页

作者： C.Wang K.Xia Department of Physics Beijing Normal University

The collective dynamics of magnetic domain wall under electric current is studied in the form of spin transfer torque(STT). The out-of-plane STT induced effective force is obtained based on the Landau-Lifshitz-Gilbert(LLG) equation including microscopic STT terms. The relation between microscopic calculations and collective description of the domain wall motion is established. With our numerical calculations based on tight binding free electron model, we find that the non adiabatic out-of-plane torque components have considerable non-local properties. It turns out that the calculated effective forces decay significantly with increasing domain wall widths.

关键词： magnetic domain Spin Transfer torque Spintronics First principle study

Relationship between microstructure and magnetic domain structure of Nd-Fe-B melt-spun ribbon magnets

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Frontiers of Materials Science 2015年第2期9卷 206-210页

作者： Masaaki TAKEZAWA Hiroyuki TANEDA Yuji MORIMOTO Department of Applied Science for Integrated System Engineering Faculty of Engineering Kyushu Institute of Technology 1-1 Sensui-cho Tobata-ku Kitakyushu Fukuoka 804-8550 Japan

The relation between the microstructure, observed using an electron probe microanalyzer, and the domain structure, observed using a Kerr microscope, was established to evaluate the effects of hot rolling and the addition of Ti-C on the c-axis orientation and the magnetization process of hot-rolled Nd-Fe-B-Ti-C melt-spun ribbons. The addition of Ti-C promotes the c-axis orientation and high coercivity in the ribbons. Elemental mapping suggests a uniform elemental distribution; however, an uneven distribution of Ti was observed in an enlarged grain with Ti-enriched points inside the grain. The reversal domains that nucleated at the Ti-enriched point inside the grain cause low coercivity.

关键词： magnetic domain microstructure Kerr effect microscope magneto-optical effect Nd-Fe-B permanent magnet

Evolution of tribo-magnetization during sliding of ferromagnetic materials

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Friction 2024年第5期12卷 906-918页

作者： Fumin GAO Laibin ZHANG Jin ZHOU Yi XIONG Jing WU Jianchun FAN China University of Petroleum-Beijing Beijing102249China Key Laboratory of Oil and Gas Safety and Emergency Technology Ministry of Emergency ManagementBeijing102249China

Sliding-induced subsurface microstructure evolution is believed to be decisive for determining the friction and wear performance of metallic contacts as well as the development of *** expects to develop a new prediction method of wear state by elucidating the correlation between subsurface microstructure evolution and corresponding magnetic domain ***,subsurface microstructure evolution including crystal and magnetic domain under tribological action is investigated *** results demonstrate that dislocation mediated plastic deformation decisively influences microstructural changes during tribological contact,further determining the magnetic domain ***,sliding-induced plastic deformation causes an increase in the width of magnetic domains,but depth-dependent derived microstructure formed under severe plastic deformation such as the refined grains and sub-grains,in turn,promoted the refinement of magnetic domains and their discontinuity,forming depth-dependent magnetic domain *** results are helpful to clarify the evolution of tribo-magnetization and the pinning effect of dislocations on magnetic domains.

关键词： tribology magnetic domain microstructure tribo-magnetization dislocations

Critical state-induced emergence of superior magnetic performances in an iron-based amorphous soft magnetic composite

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Materials Futures 2024年第2期3卷 149-160页

作者： Liliang Shao Rongsheng Bai Yanxue Wu Jing Zhou Xing Tong Hailong Peng Tao Liang Zongzhen Li Qiaoshi Zeng Bo Zhang Haibo Ke Weihua Wang Songshan Lake Materials Laboratory Dongguan 523808People’s Republic of China Institute of Physics Chinese Academy of SciencesBeijing 100190People’s Republic of China School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 100096People’s Republic of China School of Materials Science and Engineering Central South UniversityChangsha 410083People’s Republic of China Center for High Pressure Science and Technology Advanced Research Shanghai 201203People’s Republic of China Jiangsu JITRI Advanced Energy Materials Research Institute Co. LtdChangzhou 213000People’s Republic of China

Soft magnetic composites(SMCs)play a pivotal role in the development of high-frequency,miniaturization and complex forming of modern ***,they usually suffer from a trade-off between high magnetization and good magnetic softness(high permeability and low core loss).In this work,utilizing the order modulation strategy,a critical state in a FeSiBCCr amorphous soft magnetic composite(ASMC),consisting of massive crystal-like orders(CLOs,∼1 nm in size)with the feature ofα-Fe,is *** critical-state structure endows the amorphous powder with the enhanced ferromagnetic exchange interactions and the optimized magnetic domains with uniform orientation and fewer micro-vortex *** comprehensive soft magnetic properties at high frequency emerge in the ASMC,such as a high saturation magnetization(Ms)of 170 emu g^(-1)and effective permeability(µ_(e))of 65 combined with a core loss(Pcv)as low as 70 mW cm^(-3)(0.01 T,1 MHz).This study provides a new strategy for the development of high-frequency ASMCs,possessing suitable comprehensive soft magnetic performance to match the requirements of the modern magnetic devices used in the third-generation semiconductors and new energy fields.

关键词： amorphous soft magnetic composites critical state soft magnetic property rotating magnetic field annealing magnetic domain

Tailoring magnetostriction and magnetic domains of <100>-oriented Fe80Ga16Al4 alloy by magnetic field annealing

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Rare Metals 2021年第3期40卷 563-569页

作者： Xin-Lei Wang Yuan Liu Xiang Chen School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing 100084China

magnetic field annealing(MFA) was used to tailor the magnetostriction and magnetic domains of Fe80Ga16Al4 alloy,and the relationship between the two characteristics was *** -oriented alloy was prepared by the directional solidification technique and annealed for 20 min at 700℃ in a magnetic field of 250 mT along a direction 45 ° to the orientation,followed by furnace cooling in the same magnetic *** magnetostriction along the length direction(λ‖),the width direction(λ丄) and the saturation magnetostriction(λs) was changed from λ‖=208 × 10^(-6) and λ丄=-16 × 10^(-6) of the initial alloy to λ‖≈λ丄≈ 1/2 λs ≈ 112 × 10^(-6)after *** magnetic domain structure,which mainly refers to the number,size,and direction of the domains,was tailored and rearranged by *** rearrangement of the magnetic domain structure resulted in a shift of magnetostrictive properties parallel and perpendicular to the orientation for the Fe80Ga16A14 *** magnetic field annealing method can aid understanding of the relationship between the microscopic magnetic domains and the macroscopic magnetostrictive *** can also aid in further tailoring better magnetostrictive properties within magnetostrictive materials to meet the requirements of different application conditions.

关键词： FeGa alloy magnetic field annealing Magnetostriction magnetic domain

Origin of low coercivity of high La-Ce-containing Nd-Fe-B sintered magnets

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Rare Metals 2021年第1期40卷 180-184页

作者： Zhi Li Yu-Qing Li Wei-Qiang Liu Dan Wu Hao Chen Wei-Xing Xia Ming Yue College of Materials Science and Engineering Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China Key Laboratory of magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo 315201China

The origin of low coercivity of high La-Cecontaining Nd-Fe-B sintered magnets was analyzed based on characterization of the microstructure,magnetic domain structure,and magnetization reversal *** can be found that the coercivity of magnet decreases sharply and the ratio value of coercivity(H_(cj))to anisotropic field(H_(A))is below the theoretical value when the amount of La-Ce substitution for Nd is more than 40 wt%.The grain boundaries with poor magnetic isolation in the high La-Cecontaining Nd-Fe-B sintered magnets play an important role in reducing the coercivity of the *** addition,a larger proportion of the reversible portions can be found for the magnet with a large content of La-Ce,which will lead to the low performance of the magnet.

关键词： La-Ce-containing Nd-Fe-B sintered magnets magnetic properties magnetic domain Magnetization reversal