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Journal of Rare Earths 2021年第12期39卷 1554-1559,I0004页

作者： You-Song Ding Yan-Zhen Zheng Xi'an Jiaotong University Shenzhen Research Academy Shenzhen 518057China Frontier Institute of Science and Technology Xi'an Jiaotong University

Dysprosium compounds with high magnetic anisotropy are widely studied as single molecule magnets(SMMs).Here the anisotropic magnetocaloric effect in a Dy(Ⅲ)SMM,{[Dy(OSiMe_(3))_(2)(4-Mepy)5(BPh_(4))]0.5 Toluene},was studied by single *** dependent magnetization can be observed at 300 K because of its high magnetic *** behavior measured along the easy axis direction is identical to that of the polycrystalline *** magnetization from the easy axis to the hard plane gives a maximum magnetic entropy change(-ΔSR)of 3.05 J/(kg·K)at 19 K atΔB=5 T,which enables the Dy(Ⅲ)SMM to be used as a low-temperature rotating magnetic refrigerant.

关键词： Lanthanide complex magnetic anisotropy Rotate magnetocaloric effect Single molecule magnets Rare earths

Recent developments of rare-earth-free hard-magnetic materials

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Science China(Physics,Mechanics & Astronomy) 2016年第1期59卷 16-32页

作者： Da Li DeSheng Pan ShaoJie Li ZhiDong Zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the high-performance rare-earth permanent magnets, there is a much revived interest in various types of hard-magnetic materials based on rare-earth-free compounds. The 3d transition metals and their alloys with large coercivity and high Curie temperatures(working temperatures) are expected to overcome the disadvantages of rare-earth magnets. Making rare-earth-free magnets with a large energy product to meet tomorrow's energy needs is still a challenge.

关键词： rare-earth-free hard-magnetic phases coercivity magnetic anisotropy magnetic proper-ties of nanostructures

magnetic phase diagram of single-layer CrBr_(3)

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Chinese Physics B 2021年第12期30卷 577-582页

作者： Wei Jiang Yue-Fei Hou Shujing Li Zhen-Guo Fu Ping Zhang Institute of Applied Physics and Computational Mathematics Beijing 100088China Beijing University of Chemical Technology Beijing 100029China School of Physics and Physical Engineering Qufu Normal UniversityQufu 273165China

We theoretically provide a magnetic phase diagram for the single-layer(SL)CrBr_(3),which could be effectively tuned by both strain engineering and charge doping in SL-CrBr_(3).Through systematical first-principles calculations and Heisenberg model Hamiltonian simulations,three different magnetic phases in SL-CrBr_(3),which are off-plane ferromagnetic,in-plane ferromagnetic and in-plane Neél-antiferromagnetic phases,are found in the strain and charge doping regimes we ***,our results show that higher order Heisenberg exchange parameters and anisotropy exchange parameters should be taken into account for accurately illustrating the magnetic phase transition in SL-CrBr_(3).As a result,we find from the SpinW simulation that the Curie temperature is about T_(c)=38.4 K,which is well consistent with the experimental result 34 K[Nano Lett.193138(2019)].The findings here may be confirmed in future experiments,and may be useful for the potential applications of SL-CrBr_(3)in spintronics field.

关键词： magnetic anisotropy single-layer CrBr_(3) Néel-antiferromagnetic phase

Exchange couplings in magnetic films

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Chinese Physics B 2013年第2期22卷 1-22页

作者：刘伟刘雄华崔伟斌龚文杰张志东 Shenyang National Laboratory for Materials Science and International Centre for Materials Physics Institute of Metal Research Chinese Academy of Sciences

Recent advances in the study of exchange couplings in magnetic films are *** provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as anisotropic hard/soft-magnetic multilayer films,ferromagnetic/antiferromagnetic/ferromagnetic trilayers,[Pt/Co]/NiFe/NiO heterostructures,Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide（AAO） *** exchange-coupling interaction between soft-and hard-magnetic phases,interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer,ferromagnetic layer,and antiferromagnetic *** particular physical phenomena have been observed and explained.

关键词： exchange interaction magnetic anisotropy magnetic properties of interfaces(multilayers superlattices heterostructures)

A unified theory of ferromagnetic quantum phase transitions in heavy fermion metals

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Science China(Physics,Mechanics & Astronomy) 2022年第5期65卷 104-113页

作者： Jiangfan Wang Yi-Feng Yang Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of ScienceBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

Motivated by the recent discovery of a continuous ferromagnetic quantum phase transition in Ce Rh_(6)Ge_(4) and its distinction from other U-based heavy fermion metals such as UGe_(2),we develop a unified explanation of their different ground state properties based on an anisotropic ferromagnetic Kondo-Heisenberg *** employ an improved large-N Schwinger boson approach and predict a full phase diagram containing both a continuous ferromagnetic quantum phase transition for large magnetic anisotropy and first-order transitions for relatively small *** calculations reveal three different ferromagnetic phases including a half-metallic spin selective Kondo insulator with a constant *** Fermi surface topologies are found to change abruptly between different phases,consistent with that observed in UGe_(2).At finite temperatures,we predict the development of Kondo hybridization well above the ferromagnetic long-range order and its relocalization near the phase transition,in good agreement with band measurements in Ce Rh_(6)Ge_(4).Our results highlight the importance of magnetic anisotropy and provide a unified theory for understanding the ferromagnetic quantum phase transitions in heavy fermion metals.

关键词： ferromagnetic Kondo lattice magnetic anisotropy ferromagnetic quantum phase transition Schwinger boson

magnetic dynamics of two-dimensional itinerant ferromagnet Fe_(3)GeTe_(2)

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Chinese Physics B 2021年第9期30卷 506-512页

作者： Lijun Ni Zhendong Chen Wei Li Xianyang Lu Yu Yan Longlong Zhang Chunjie Yan Yang Chen Yaoyu Gu Yao Li Rong Zhang Ya Zhai Ronghua Liu Yi Yang Yongbing Xu Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and EngineeringNanjing UniversityNanjing 210093China Jiangsu Provincial Key Laboratory for Nanotechnology School of PhysicsNanjing UniversityNanjing 210093China Department of Physics Southeast UniversityNanjing 211189China York-Nanjing Joint Centre for Spintronics and NanoEngineering Department of Electronic EngineeringUniversity of YorkYork YO105DDUnited Kingdom Jiangsu Key Laboratory of Opto-Electronic Technology Center for Quantum Transport and Thermal Energy ScienceSchool of Physics and TechnologyNanjing Normal UniversityNanjing 210023China

Among the layered two-dimensional ferromagnetic materials(2D FMs),due to a relatively high T_(C),the van der Waals(vdW)Fe_(3)GeTe_(2)(FGT)crystal is of great importance for investigating its distinct magnetic ***,we have carried out static and dynamic magnetization measurements of the FGT crystal with a Curie temperature TC≈204 *** M-H hysteresis loops with in-plane and out-of-plane orientations show that FGT has a strong perpendicular magnetic anisotropy with the easy axis along its ***,we have calculated the uniaxial magnetic anisotropy constant(K_(1))from the SQUID *** dynamic magnetic properties of FGT have been probed by utilizing the high sensitivity electron-spin-resonance(ESR)spectrometer at cryogenic *** on an approximation of single magnetic domain mode,the K_(1)and the effective damping constant(αeff)have also been determined from the out-of-plane angular dependence of ferromagnetic resonance(FMR)spectra obtained at the temperature range of 185 K to T_(C).We have found large magnetic damping with the effective damping constantαeff~0.58 along with a broad linewidth(ΔH_(pp)>1000 Oe at 9.48 GHz,H||c-axis).Our results provide useful dynamics information for the development of FGT-based spintronic devices.

关键词： two-dimensional ferromagnet ferromagnetic resonance magnetic anisotropy magnetic damping

Seeking magneto-structural correlations in easily tailored pentagonal bipyramid Dy (Ⅲ) single-ion magnets

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Science China Chemistry 2020年第8期63卷 1066-1074页

作者： Guo-Zhang Huang Ze-Yu Ruan Jie-Yu Zheng Yan-Cong Chen Si-Guo Wu Jun-Liang Liu Ming-Liang Tong Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education School of ChemistrySun Yat-Sen UniversityGuangzhou 510275China

Controlling molecular magnetic anisotropy via structural engineering is delicate and fascinating,especially for single-molecule magnets(SMMs).Herein a family of dysprosium single-ion magnets(SIMs)sitting in pentagonal bipyramid geometry have been synthesized with the variable-size terminal ligands and counter anions,through which the subtle coordination geometry of Dy(Ⅲ)can be finely tuned based on the size *** effective energy barrier(Ueff)successfully increases from 439 to 632 K and the magnetic hysteresis temperature(under a 200 Oe/s sweep rate)raises from 11 to 24 *** on the crystal-field theory,a semi-quantitative magneto-structural correlation deduced experimentally for the first time is revealed that the Ueff is linearly proportional to the structural-related value S20 corresponding to the axial coordination bond lengths and the bond *** the evaluation of the remanent magnetization from hysteresis,quantum tunneling of magnetization(QTM)is found to exhibit negative correlation with the structural-related value Stun corresponding to the axial coordination bond angles.

关键词： single-molecule magnets magnetic anisotropy crystal field magneto-structural correlation

Temperature Dependence of the Magnetocrystalline anisotropy in Nd_2Co_(14)B Compound

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Rare Metals 1992年第3期11卷 195-198页

作者：赵志刚孙校开庄育智葛运培王景禹 Institute of Metal Research Academia SinicaShenyang 110015P.R.China Shenyang College of Architectural Engineering Shenyang 110015P.R.China

Easy and hard magnetization curves of Nd_2Co_(14)B compound have been measured with extracting-sample-magnetometer(μ_0H_(max)=6T)at 10～300 *** anisotropy constants K_1 and K_2 have been determined by fitting the hard magnetization curves,in which only K_1 ,K_2 and misalignment angle have been taken as fitting *** values of K_1 and K_2 at 4.2 K were derived by extrapolation. anisotropy coefficients,x_2~° and x_4~°were derived from the anisotropy *** anisotropy constant K_2 increases rapidly with increasing temperature when TT_(sr).The temperature depen- dence of the magnetic anisotropy coefficient x_2~° was fitted with the *** anisotropy coefficients x_2~° can be well described by the tenth-power law from 4.2 K to T_(sr)and by the sixth-power law from T_(sr_ to 300 K.

关键词： Nd_2Co_(14)B magnetic anisotropy anisotropy constants

Characterization of CoPt nanowire fabricated by glancing angle deposition

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Chinese Physics B 2015年第5期24卷 438-443页

作者：锻代聪张政军史蹟中村吉男 School of Materials Science and Engineering Key Laboratory of Advanced Materials Tsinghua University Department of Metallurgy and Ceramics Science Tokyo Institute of Technology

CoPt and Co nanowire films were deposited by the Glancing Angle Deposition （GLAD） method. All samples are deposited on Si substrates that were covered by polystyrene spheres to assist the alignment of nanowires. SEM observation results show that the length and diameter of nanowires are uniform for all samples. According to the result of XRD, the crystal structure of CoPt is fcc. The angular dependence of magnetization of the nanowires shows that the easy axis of magnetization is along the growth direction of the nanowires.

关键词： nanowires magnetic anisotropy magnetic properties

Template-assisted growth of Co-BaTiO_(3) vertically aligned nanocomposite thin films with strong magneto-optical coupling effect

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Nano Research 2024年第4期17卷 3130-3138页

作者： Zedong Hu Juanjuan Lu Hongyi Dou Jianan Shen James PBarnard Juncheng Liu Xinghang Zhang Haiyan Wang School of Electrical and Computer Engineering Purdue UniversityWest LafayetteIN 47906USA School of Materials Engineering Purdue UniversityWest LafayetteIN 47906USA

Oxide-metal based nanocomposite thin films have attracted great interests owing to their unique anisotropic structure and physical properties.A wide range of Au-based oxide-metal nanocomposites have been demonstrated,while other metal systems are scarce due to the challenges in the initial nucleation and growth as well as possible interdiffusions of the metallic *** this work,a unique anodic aluminum oxide(AAO)template was used to grow a thin Co seed layer and the following self-assembled metal-oxide(Co-BaTiO_(3))vertically aligned nanocomposite thin film *** AAO template allows the uniform growth of Co-seeds and successfully deposition of highly ordered Co pillars(with diametermagnetic anisotropy and strong magneto-optical coupling properties have been observed.A thin Au-BaTiO_(3) template was also later introduced for further enhanced nucleation and ordered growth of the *** the advantage of such a unique nanostructure,a large out-of-plane(OP)coercive field(Hc)of~5000 Oe has been achieved,making the nanocomposite an ideal candidate for high density perpendicular magnetic tunneling junction(p-MTJ).A strong polar magneto-optical Kerr effect(MOKE)has also been observed which inspires a novel optical-based reading method of the MTJ states.

关键词： vertically aligned nanocomposite(VAN) Co BaTiO_(3) thin film magneto-optical coupling magnetic anisotropy