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Inter-granular exchange coupling and magnetic anisotropy of Ta/Ru/Co-23 at%Pt perpendicular thin films with different Ru underlayer thicknesses

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Rare Metals 2016年第6期35卷 463-470页

作者： Na Xiao Bo Yang Jian-Sheng Wang Song Li Yu-Ping Ren Gao-Wu Qin Research Academy Northeastern University Shenyang 110819China Key Laboratory for Anisotropy and Texture of Materials (MoE) School of Materials Science and Engineering Northeastern University Shenyang 110819 China

In the present work, a series of Ta/Ru/Co- 23 at%Pt thin films with varied Ru underlayer thicknesses were fabricated by magnetron sputtering. All of the films show c-axis preferred orientation perpendicular to the film surface. The drop of c/a ratio and lattice expansion of Co- Pt layer with the increase in Ru underlayer thickness was revealed by X-ray diffraction （XRD）. The coercivity of the Ta/Ru/Co-Pt thin films increases drastically with Ru underlayer thickness increasing, due to the enhancement of effective magneto-crystalline anisotropy constant and exchange decoupling of magnetic nano-grains. The enhancement of effective magneto-crystalline anisotropy constant is ascribed to the lattice deformation of Co-Pt layer by mismatching the Ru layer and Co-Pt surface. Moreover, the exchange decoupling of magnetic nanograins is attributed to the further isolation of magnetic nano-grains.

关键词： Co-Pt Perpendicular recording media Crystallographic orientation exchange coupling

Effect of chromium interlayer on magnetic exchange coupling of SmCo/Cr/TbFeCo multilayer thin films

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Journal of Rare Earths 2008年第3期26卷 375-377页

作者：张峰黄致新兰智高崔增丽郭继花程伟明杨晓非 College of Physical Science and Technology Central China Normal University College of Physical Science and Technology Huanggang Normal University Department of Electronic Science and Technology Huazhong University of Science and Technology

A series of SmCo/Cr/TbFeCo multilayer thin films with perpendicular anisotropy were prepared by RF- magnetron sputtering system, and the effects of Cr interlayer thickness on magnetic properties and interlayer exchange coupling were investigated. It was found that the magnetic properties varied with the thickness of Cr interlayer, especially the values of saturation magnetization Ms and the coercivity Hc fluctuated periodically with the thickness of Cr interlayer. STM images revealed that the variation of coercivity Hc was attributed to the microstructure change of SmCo layer influenced by Cr interlayer, and the variation of Ms was related to interlayer exchange coupling.

关键词： interlayer exchange coupling multilayer thin films rare earths

Effect of exchange coupling on magnetic property in Sm–Co/α-Fe layered system

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Chinese Physics B 2016年第3期25卷 380-386页

作者：桑成祥赵国平夏卫星万秀琳 F J Morvan 张溪超谢林华张健杜娟闫阿儒刘平 College of Physics and Electronic Engineering Sichuan Normal University Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of Sciences Department of Physics University of Texas at Arlington

The hysteresis loops as well as the spin distributions of Sm-Co/a-Fe bilayers have been investigated by both three- dimensional （3D） and one-dimensional （1D） micromagnetic calculations, focusing on the effect of the interface exchange coupling under various soft layer thicknesses ts. The exchange coupling coefficient Alas between the hard and soft ,layers varies from 1.8 x10-6 erg/cm to 0.45 x 10-6 erg/cm, while the soft layer thickness increases from 2 nm to 10 nm. As the exchange coupling decreases, the squareness of the loop gradually deteriorates, both pinning and coercive fields rise up monotonically, and the nucleation field goes down. On the other hand, an increment of the soft layer thickness leads to a significant drop of the nucleation field, the deterioration of the hysteresis loop squareness, and an increase of the remanence. The simulated loops based on the 3D and 1D methods are consistent with each other and in good agreement with the measured loops for Sm-Co/a-Fe multilayers.

关键词： hysteresis loops exchange coupling micromagnetics hard/soft bilayers

Effect of zirconium content on exchange coupling and magnetization reversal of nanocrystalline Nd_(12.3)Fe_(81.7-x)Zr_xB_6 alloy

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Journal of Rare Earths 2011年第10期29卷 939-942页

作者：包小倩高学绪朱洁周寿增 State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The effect of Zr content on exchange coupling and magnetization reversal of the Ndl2.3Fe81.7_xZrxB6 （x=0-3.0） ribbons was systematically investigated. Interaction domains were imaged by magnetic force microscopy （MFM）. The strength of interactions determined by Wohlfarth＇s analysis increased first with Zr content x increasing, reached the maximum value at x=l.5, and then decreased with x further increasing. Initial magnetization curves and dependence of coercivity and remanence on applied magnetic field showed that the mechanism of coercivity in all samples was mainly of exchange coupling pinning type, which was enhanced with x increasing. It was found by three-dimensional atom probe （3DAP） that Zr atoms did not partition into the Nd2Fe14B hard magnetic phase, but significantly enriched at the interfacial region.

关键词： nanocrystalline Nd-Fe-B magnets exchange coupling magnetization reversal microstxucture rare earths

exchange-coupling-induced fourfold magnetic anisotropy in CoFeB/FeRh bilayer grown on SrTiO_(3)(001)

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Chinese Physics B 2022年第8期31卷 605-611页

作者： Qingrong Shao Jing Meng Xiaoyan Zhu Yali Xie Wenjuan Cheng Dongmei Jiang Yang Xu Tian Shang Qingfeng Zhan Key Laboratory of Polar Materials and Devices(MOE) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo 315201China

exchange coupling across the interface between a ferromagnetic(FM)layer and an antiferromagnetic(AFM)or another FM layer may induce a unidirectional magnetic anisotropy and/or a uniaxial magnetic anisotropy,which has been extensively studied due to the important application in magnetic materials and *** this work,we observed a fourfold magnetic anisotropy in amorphous Co Fe B layer when exchange coupling to an adjacent Fe Rh layer which is epitaxially grown on an SrTiO_(3)(001)*** the temperature rises from 300 K to 400 K,Fe Rh film undergoes a phase transition from AFM to FM phase,the induced fourfold magnetic anisotropy in the Co Fe B layer switches the orientation from the Fe Rhto Fe Rhdirections and the strength is obviously *** addition,the effective magnetic damping as well as the two-magnon scattering of the Co Fe B/Fe Rh bilayer also remarkably increase with the occurrence of magnetic phase transition of Fe *** exchange bias is observed in the bilayer even when Fe Rh is in the nominal AFM state,which is probably because the residual FM Fe Rh moments located at the interface can well separate the exchange coupling between the below pinned Fe Rh moments and the Co Fe B moments.

关键词： magnetic anisotropy phase transition CoFeB/FeRh exchange coupling

Large coercivity and unconventional exchange coupling in manganese-oxide-coated manganese gallium nanoparticles

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Chinese Physics B 2014年第8期23卷 95-98页

作者：冯俊宁刘伟耿殿禹马嵩余涛赵晓天代志明赵新国张志东 Shenyang National Laboratory for Materials Science and International Center for Materials Physics Institute of Metal ResearchChinese Academy of Sciences

The microstructures and magnetic properties of nanoparticles, each composed of an antiferromagnetic （AFM） manganese-oxide shell and a ferromagnetic-like core of manganese-gallium （MnGa） compounds, are studied. The coreshell structure is confirmed by transmission electron microscope （TEM）. The ferromagnetic-like core contains three kinds of MnGa binary compounds, i.e., ferrimagnetic （FI） DO22-type MnaGa, ferromagnetic （FM） Mn8Gas, and AFM DO19-type Mn3Ga, of which the first two correspond respectively to a hard magnetic phase and to a soft one. Decoupling effect between these two phases is found at low temperature, which weakens gradually with increasing temperature and disappears above 200 K. The exchange bias （EB） effect is observed simultaneously, which is caused by the exchange coupling between the AFM shell and FM-like core. A large coercivity of 6.96 kOe （1Oe = 79.5775 A·m^-1） and a maximum EB value of 0.45 kOe are achieved at 300 K and 200 K respectively.

关键词： nanoparticle core-shell structure exchange coupling

Slow magnetic relaxation in a 3D dysprosium(Ⅲ)-fluoro-oxalate framework containing zig-zag [Dy-F]n chains

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Journal of Rare Earths 2023年第1期41卷 100-107页

作者： Leilei Li Yifan Fang Shuang Liu Mingfei Hu Wenzhen Wang College of Chemistry and Chemical Engineering Xi'an Shiyou UniversityXi'an 710065China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin 300071China

Dysprosium complexes based on [F-Dy] or near-linear [F-Dy-F] unit are of great concern in the field of single-molecule magnets due to their large magnetic ***,the crystal structure and the magnetic relaxation dynamics were reported for a three-dimensional(3 D) metal-organic framework(MOF):[DyF(C_(2)O_(4))(H_(2)O)2]n·2nH_(2)O(1),which is the unique MOF containing zig-zag [Dy-F]_(n) *** susceptibility characterization reveals that 1 is one of the few 3 D MOFs which show slow magnetic relaxation under zero dc *** the effective energy barrier of 72 K for 1 is also higher than most Dy-based 3 D *** diamagnetic ion dilution study shows that the ferromagnetic exchange couplings mainly transmitted by F^(-) bridges in 1 contribute little to the energy barrier,but effectively suppress the quantum tunneling process and result in a smooth hysteresis loop with no waist-restricted step.

关键词： Dysprosium complex Fluoride Magnetic property Slow magnetic relaxation exchange coupling Rare earths

Structural transformation and magnetic properties of Sm-Fe alloys with V doping

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Rare Metals 2022年第7期41卷 2349-2352页

作者： Yong-Jun Mao Jin-Ling Jin Jia-Jun Xie Yang Luo Kuo-She Li Wen-Long Yan Dun-Bo Yu Hong-Wei Li National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsBeijing 100088China Grirem Advanced Materials Co.Ltd. Beijing 100088China

A systematical investigation was carried out on structure and magnetic properties in SmFe_(9-x)V_(x)(x=0.4,0.8,1.2)compounds prepared by a single-roller quenching *** high cool-down rate leads to metastable TbCu_(7) phase in the parent compound,which gradually transforms into equilibrium ThMn_(12) structure with V-doping content *** Curie temperature increases from 470 to 590 K with V doping,which is consistent with the phase ***,simultaneous increase in both coercivity and remanence is resulted by V doping,reaching the highest value of 685 kA·m^(-1)and 44.8×10^(-3)A·m^(2)·g^(-1)in x=1.2 compound,*** phenomenon can be explained by the combination of phase transformation and intergranular exchange coupling throughδM-H plots.

关键词： Phase transformation Magnetic properties exchange coupling Element doping ThMn12-type phase

Effect of La-Y co-substitution on magnetic properties and microstructure of NdFeB alloy ribbons

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Journal of Rare Earths 2022年第12期40卷 1894-1898,I0003页

作者： Chuanjia Zhao Qingzheng Jiang Sajjad Ur Rehman Xiang Li Youwei Chen Jie Song Zhenchen Zhong Jiangxi Key Laboratory for Rare Earth Magnetic Materials and Devices&College of Rare Earths Jiangxi University of Science and TechnologyGanzhou 341000China Fujian Key Laboratory for Rare Earth Functional Materials Longyan 366300China

Committed to obtaining cost-effective NdFeB based permanent magnets,Nd_(27-x)La_(3)Y_(x)Fe_(bal)Al_(0.1)Cu_(0.1)B_(1)(x=0-3)alloys were fabricated to detect the magnetic properties and *** x=1.8,coercivity of 1004 kA/m and the magnetic remanence of 0.75 T are obtained,which are close to those of the original Nd_(30)Fe_(bal)A_(l0.1)Cu_(0.1)B_(1)alloy *** temperature coefficient of coercivity(β)and the temperature coefficient of remanence(α)of the LaY-substituted alloys are better than those of the original *** research results manifest that La is mainly distributed in the grain boundary phases and plays the role of refining the main grains,optimizing the grain boundary phases and improving the wettability between the main phases and the grain boundary phases,while Y tends to enrich in the main phases and enhances the short-range exchange coupling.

关键词： Magnetic properties Microstructure Alloy ribbons Main phase exchange coupling Rare earths