检索结果-南通市图书馆

Chinese Physics B 2024年第5期33卷 688-694页

作者：赵乾张腾飞何斌李子木张森富于国强王建波刘青芳魏晋武 Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Special Functional Materials and Structural Design Ministry of EducationLanzhou UniversityLanzhou 730000China

Antiferromagnet(AFM)/ferromagnet(FM)heterostructure is a popular system for studying the spin–orbit torque(SOT)of AFMs.However,the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field,namely the magnetic moment drag effect,which further influences the characteristic of SOT efficiency.In this work,we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance(ST-FMR)method.A full analysis on the AFM/FM systems with exchange bias is performed,and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free energy.The ST-FMR results can be well fitted by this model.We obtained the relative accurate SOT efficiencyξ_(DL)=0.058 for the IrMn film.This work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.

关键词： antiferromagnets spin-orbit torque exchange bias spin torque ferromagnetic resonance

exchange bias on polycrystalline BiFeO3/CO2Fe(Al0.5Si0.5) heterostructures

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第1期36卷 32-36页

作者： Shi-Zhe Wu Yong Wu Shao-Qian Yin Xiao-Guang Xu Jun Miao Yong Jiang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Polycrystalline antiferromagnetic BiFeO(BFO)thin films were grown on Si/Si O/Ti/Pt(111) substrates by pulsed laser deposition and then ferromagnetic films CoFe(AlSi)(CFAS) by magnetron sputtering. After fabrication, the films were vacuum-annealed under a 0.1-T magnetic field at different temperatures from 150 to 500 °C.The exchange bias field can be tuned by the annealing temperature for the heterostructures, and the electric domain size can be controlled by the crystal grain size. A large exchange bias of about 5*10T is observed in one of the samples. It can be speculated that the crystal grain sizes are the key element in determining the exchange bias and coercivity of the films annealed at the temperature of higher than Neel temperature(T N) of BFO. Furthermore, it is possible to extend spin theories from single-crystal BFO system to polycrystalline BFO system.

关键词： exchange bias BiFeO3 Polycrystalline Domain walls

Inverse dependence of exchange bias and coercivity on cooling field caused by interfacial randomization in nanosystems with Co sparsely distributed in CoFe_(2)O_(4) matrix

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第3期98卷 258-267页

作者： Song Yang Yong Hu Department of Physics College of SciencesNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

We conceive a model of nanosystems where Co is uniformly,randomly distributed into a CoFe_(2)O_(4)(CFO)matrix,and study the influences of composition and CFO antiferromagnetic exchange coupling(JCFO)on zero-field-cooled/field-cooled magnetization behavior and the dependencies of exchange bias field(H_(E))and coercivity(H_(C))on Co/CFO interfacial coupling(J_(Co/CFO)),composition and cooling field(H_(FC)),based on a modified Monte Carlo method.With decreasing temperature,the zero-field-cooled and field-cooled magnetization curves are overlapped and increasing initially,and then splitting at a critical temperature(T_(P)),below which the field-cooled magnetization continues increasing while the zero-field-cooled magnetization exhibits a peak and drops,indicating a magnetically frozen state.A larger J_(CFO) induces an elevated T_(P) and a reduced magnetization,while the opposite results are obtained by a higher Co occupation fraction(P_(Co)).On the other hand,H_(E) is nonmonotonic with J_(Co/CFO )and the peak decreases and shifts to a lower J_(Co/CFO)value for a larger P_(Co).H_(C) increases monotonically with increasing J_(Co/CFO).Moreover,H_(E) is inversely proportional to P_(Co) when PCo varies from 0.11 to 0.30,indicating the exchange bias is still an interfacial effect.Finally,for a nonzero J_(CFO),H_(E) may be suppressed and accompanied by the recovery of H_(C) with increasing H_(FC).Otherwise,H_(C) for zero J_(CFO) becomes high and insensitive to H_(FC).It is ascribed to the uniform contact between Co and CFO,leading to the Co magnetization reversal and the CFO magnetization precisely controlled by H_(FC).This work opens a new avenue to control the exchange bias in nanosystems through interfacial randomization.

关键词： exchange bias Ferromagnetic occupation fraction Cooling field Monte Carlo simulation

exchange bias in ferromagnet/antiferromagnet bilayers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第2期23卷 1-13页

作者：时钟杜军周仕明 Shanghai Key Laboratory of Special Artificial Microstructure Materials & Technology and School of Physics Science and Engineering Tongji UniversityShanghai 200092 Department of Physics Nanjing University

Since the exchange bias （EB） effect was discovered in the Co/CoO core-shell nanoparticles, it has been extensively studied in various ferromagnet （FM）/antiferromagnet （AFM） bilayers due to its crucial role in spintronics devices. In this article, we review the investigation of the EB in our research group. First, we outline basic features of the EB, including the effects of the constituent layer thickness, the microstructure and magnetization of the FM layers, and we also discuss asymmetric magnetization reversal process in wedged-FM/AFM bilayers. Secondly, we discuss the mechanisms of the positive EB and the perpendicular EB. Thirdly, we demonstrate the hysteretic behavior of the angular dependence of the EB and analyze the EB training effect. Finally, we discuss the roles of the rotatable anisotropy in the two phenomena.

关键词： exchange bias ferromagnet antiferromagnet bilayers

Room-temperature electric control of exchange bias effect in CoO1-δ/Co films using Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (110) substrates

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第9期29卷 564-568页

作者：闻馨吴锐杨文云王常生刘顺荃韩景智杨金波 State Key Laboratory for Mesoscopic Physics and School of Physics Peking UniversityBeijing 100871China Beijing Key Laboratory for Magnetoelectric Materials and Devices Beijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China

Significant electric control of exchange bias effect in a simple CoO1-δ/Co system, grown on piezoelectric Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (110) (PMN-PT) substrates, is achieved at room temperature. Obvious changes in both the coercivity field (HC) and the exchange bias field (HE), of 31% and 5%, respectively, have been observed when the electric field is applied to the substrate. While the change of coercivity is related to the enhanced uniaxial anisotropy in the ferromagnetic layer, the change of the exchange bias field can only originate from the spin reorientation in the antiferromagnetic CoO1-δ layer caused by the strain-induced magnetoelastic effect. A large HE/HC > 2, and HE~ 110 Oe at room temperature, as well as the low-energy fabrication of this system, make it a practical system for spintronic device applications.

关键词： electric control exchange bias PMN-PT magnetic anisotropy

Role of competing interactions on dynamic relaxation and exchange bias in spin-glass/ferromagnet bilayer

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第16期47卷 63-69页

作者： Xiaodan Chi Yong Hu Department of Physics College of SciencesNortheastern UniversityShenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

When a ferromagnet(FM)couples to a spin glass(SG),the hidden nature of SG may imprint on the FM via their interfacial coupling,probably resulting in elongated magnetic relaxation and enhanced unidirectional and uniaxial anisotropies.In parallel with the study of interfacial roles,e.***.interfacial coupling and matching,we focused on the influence of the competing interactions in SG(JSG)on the magnetic relaxation properties of SG/FM bilayer and the FM magnetization reversal involving exchange bias field(HE)and coercivity(HC).A fastest decay of relaxation in SG/FM bilayer is found at an intermediate JSG^5.2 erg/cm2 and the relaxation parameters related to JSG are nonmonotonic.On the other hand,a pronounced HE of^0.26 kOe is observed at small JSG,and as JSG increases larger than 2.275 erg/cm2,HE decreases by an order of magnitude and levels off,i.e.,a net EB remains.He is sensitive to JSG only at JSG above 2.275 erg/cm2 and exhibits a minimum value at JSG=4.55 erg/cm2,just below 5.2 erg/cm2 where the relaxation decay is the fastest.Microscopic analysis unravels that the net magnetization associated with unidirectional magnetic stabilization and the large-area FM-like domains in SG are favored at small JSG,while with increasing JSG,the SG spins spontaneously reverse and thus the energy barriers are smeared out.A high susceptibility and a strong interfacial coupling lead to FM magnetization reversal under weaker fields and thus a decrease in coercivity.For too large JSG(exceeding 5.2 erg/cm2),magnetic frustration extends over the domains in SG meanwhile fierce energy competition occurs frequently,resembling enhanced quantum fluctuations.As a result,dynamic relaxation and statistic coercivity are both recovered.This work tells us that the independent modulations of unidirectional and uniaxial anisotropies are possible in SG-based systems through precisely controlling JSG,which is desired for application in the read/write head in future data storage media.

关键词： Spin glass Competing interaction Magnetic relaxation exchange bias Coercivity Monte Carlo simulation

Magnetoresistance and exchange bias in high Mn content melt-spun Mn_(46)Ni_(42)Sn_(11)Sb_1 alloy ribbon

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第5期25卷 316-320页

作者：黄庆学陈峰华张敏刚许小红 Heavy Machinery Engineering Research Center of Education Ministry College of Mechanical EngineeringTaiyuan University of Science and Technology School of Chemistry and Materials Science Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education Shanxi Normal University

Highly textured Heusler alloy Mn_（46）Ni_（42）Sn_（11）Sb_1 ribbons were prepared by melt spinning. The annealed high Mn content Mn46Ni42Sn11Sb1 ribbon cross-section microstructure, crystal structure, martensitic transformation（MT）, and magnetoresistance（MR） properties were investigated. The MR in the annealed ribbon was assessed by the magnetic field direction perpendicular to the ribbon surface with the magnetic field up to 30 k Oe. The large negative value of 25% for MR was obtained at 244 K. The exchange bias（EB） effects of the as-spun and annealed ribbons were investigated. After annealing, the EB effects have been improved by about 25 Oe at the temperature of 50 K. The magnetizations have increased approximately by 10% more than the as-spun ribbon.

关键词： Heusler alloy melt spun magnetoresistance exchange bias

Stacking-dependent exchange bias in two-dimensional ferromagnetic/antiferromagnetic bilayers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第1期33卷 708-714页

作者：李慧平潘帅唯王喆向斌朱文光 International Center for Quantum Design of Functional Materials Hefei National Research Center for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China Department of Physics University of Science and Technology of ChinaHefei 230026China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Department of Materials Science&Engineering University of Science and Technology of ChinaHefei 230026China

A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations,we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications.

关键词： exchange bias two-dimensional ferromagnetic/antiferromagnetic bilayers asymmetric magnetic interaction

Asymmetric exchange bias training effect in spin glass(FeAu)/FeNi bilayers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第10期23卷 513-518页

作者：芮文彬何茂诚游彪时钟周仕明肖明文高远张维孙力杜军 National Laboratory of Solid State Microstructures and Department of Physics Nanjing University Department of Physics Tongji University Department of Mechanical Engineering and Texas Center for Superconductivity (TcSUH) University of Houston

A significant exchange bias （EB） traimng ettect has been observea in sputter deposited FeAu/FeNi bilayers, wherein the exchange field （HE） exhibits a special sign-changeable temperature dependence. Very interestingly, despite the absence of multiple easy axes in the FeAu spin glass （SG） layer, HE drops abruptly between the first and second magnetic cycles, which is followed by a more gradual continuous change in the subsequent cycles. This training behavior cannot be described by the empirical n-1/2 law because of the asymmetric magnetization reversal processes. We propose modifying Binek＇s model to include the asymmetric changes of the pinning SG spins at the descending and ascending branches. This new model successfully describes the EB training effect in FeAu/FeNi bilayers.

关键词： exchange bias training effect spin glass

Multiple sign reversals of the exchange bias field in polycrystalline SmCr_(0.9)Fe_(0.1)O_3

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第12期23卷 453-457页

作者：房勇颜士明龚元元朱卫利曹庆琪王敦辉都有为 Jiangsu Key Laboratory for Nano Technology and National Laboratory of Solid State Microstructures Nanjing University

We synthesize the perovskite compound Sm Cr0.9Fe0.1O3 by the sol–gel method and investigate its exchange bias properties through thermomagnetic and isothermal magnetization measurements. The sign reversals of the exchange bias field are observed at the magnetization compensation temperatures 29.6 K and 96.2 K. It is demonstrated that the occurrence of the exchange bias originates from the antiferromagnetic coupling between the Cr-rich and Fe–Cr regions, of which the net magnetization is temperature-dependent. These results imply that there are potential applications in single systems with sign reversals of both magnetization and exchange bias.

关键词： magnetism antiferromagnetic exchange bias