Flexible magnetic devices, i.e., magnetic devices fabricated on flexible substrates, are very attractive in applications such as detection of magnetic field in an arbitrary surface, non-contact actuators, and microwav...Flexible magnetic devices, i.e., magnetic devices fabricated on flexible substrates, are very attractive in applications such as detection of magnetic field in an arbitrary surface, non-contact actuators, and microwave devices, due to their stretchable, biocompatible, light-weight, portable, and low cost properties. Flexible magnetic films are essential for the realization of various functionalities of flexible magnetic devices. To give a comprehensive understanding for flexible magnetic films and related devices, recent advances in the study of flexible magnetic films are reviewed, including fabrication methods, magnetic and transport properties of flexible magnetic films, and their applications in magnetic sensors, actuators, and microwave devices. Our aim is to foster a comprehensive understanding of these films and devices. Three typical methods have been introduced to prepare the flexible magnetic films, by deposition of magnetic films on flexible substrates, by a transfer and bonding approach or by including and then removing sacrificial layers. Stretching or bending the magnetic films is a good way to apply mechanical strain to them, so that magnetic anisotropy, exchange bias, coercivity, and magnetoresistance can be effectively manipulated. Finally, a series of examples is shown to demonstrate the great potential of flexible magnetic films for future applications.展开更多
200 nm thick Fe-N magnetic thin films were deposited on glass substrates by RF sputtering. The as-deposited films have high saturation magnetization but their coercivity is also higher than what is needed Therefore it...200 nm thick Fe-N magnetic thin films were deposited on glass substrates by RF sputtering. The as-deposited films have high saturation magnetization but their coercivity is also higher than what is needed Therefore it is very important to reduce coercivity. The samples were vacuum annealed at 250℃ under 12000 A/m magnetic field. When the N content was in the range of 5-7 at. pct, the thin films consisted of α' +α' after heat treatment and had excellent soft magnetic properties of 4πMs=2.4 T, HC <80 A/m. However, the thickness of a recording head was 2μm, and Hc increased as thickness increased. In order to reduce the Hc, the sputtering power was raised from 200 W to 1000 W to reduce the grain size. 2μm Fe-N thin films were vacuum annealed under the same condition, when the N content was in the range of 5.9-8.5 at. pct, the thin films kept its excellent magnetic properties of 4πMs=2.2 T, HC <80 A/m. The properties of the films meet the need of a recording head material used in the dual-element GMR/inductive heads.展开更多
Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy, it has been found that the microstruc...Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy, it has been found that the microstructure and the magnetic properties of films were influenced greatly by the bath pH. At the bath pH 8.06, the grain size and coercivity of the films reach maximuml while the squareness (Mr/Ms) of MH curves reaches minimum. The Henkel plots indicates that the exchange-coupling interaction is very weak at this pH, which may be caused by phase-separation and large grain size, and then results in the lowest squareness. At pH above 8.5, obvious exchange-coupling interaction is observed because of the inexistence of phase-separation and the refinement of grain size.展开更多
A single layer of CoFeB and a multilayer of CoFeB MgO films are prepared by means of DC/RF magnetron sputter deposition. The excellent microwave properties and high electrical resistivity are simultaneously achieved i...A single layer of CoFeB and a multilayer of CoFeB MgO films are prepared by means of DC/RF magnetron sputter deposition. The excellent microwave properties and high electrical resistivity are simultaneously achieved in the discontinuous multilayer structure of [Co44Fe44B12(0.7nm)/MgO(0.4nm)]40 film. This film has a high permeability (μ′) (larger than 100 below 2.1 GHz), a high magnetic loss (μ″) (larger than 100 in a range from 1.5 to 3.3GHz), a resistivity of 3.3 × 10^3μΩ. cm, a saturation magnetization of 1.2 T, and an in-plane uniaxial anisotropy field of 5.5 kA/m. The microstructure and the surface topography of the film are also analysed. The relatively large surface roughness for the discontinuous film is responsible for the wide frequency band of magnetic loss. The magnetic loss and the high resistivity indicate that the discontinuous CoFeB MgO multilayer film has potential applications in microwave absorbers and electromagnetic interference (EMI) shielding materials in a GHz frequency range.展开更多
It is proposed that the magnetization-induced anisotropy of magnetic films of cubic crystal structure originates from the anisotropy of atomic pair ordering, shape anisotropy, and strain anisotropy resulting from the ...It is proposed that the magnetization-induced anisotropy of magnetic films of cubic crystal structure originates from the anisotropy of atomic pair ordering, shape anisotropy, and strain anisotropy resulting from the constraint of the magnetostriction strain imposed on the film by the substratc. Calculated are the three anisotropy constants and their sum K vs temperature for Ni, Fe, and 55%Ni-Fe films; the room temperature (RT) constants vs the substrate temperature Tt during deposition or annealing after deposition for Ni and 50%Ni Co films; the RT constants vs com- position fraction for Fe-Ni films with Tt = RT, 250℃ and 450℃, Co Ni films at Tt = RT, 100℃ and 320℃, and Fe-Co films with Tt = RT and 300℃; the spread of RT K vs composition fraction for Fe Ni films; and RT △K/K vs composition fraction for Fe-Ni and Co Ni films, where △K denotes the variation of K of the film that is detached from its substrate. The calculated curves well accord with the measurements. The irrelevancy of K to the substrate material and the fast kinetics of the annealing in a field applied in the direction of the hard axis are explained reasonably.展开更多
The c-axis oriented hcp-Co_(81)Ir_(19)magnetic films were prepared on different seed layers(Ni,Cu,Ir,Pt,Au,and No seed).We systematically investigated the impact that surface-free energy and strain energy have on the ...The c-axis oriented hcp-Co_(81)Ir_(19)magnetic films were prepared on different seed layers(Ni,Cu,Ir,Pt,Au,and No seed).We systematically investigated the impact that surface-free energy and strain energy have on the orientation and defects and/or internal stress of the grains by increasing the lattice mismatch ratio.Moreover,the initial permeability and the natural resonance frequency were discussed in great detail using a comparison between calculated values and experimental values.We found that the almost unchanged 4πM_(s) andμ_(i) are not affected,while the changed H_(c),intrinsic K_(grain),and f_(r) are strongly dependent on the seed layer and seed layer material.Moreover,the extracted damping constant is sensitive to the defects and/or internal stress and orientation of the grains.Therefore,the soft magnetic properties and microwave properties are adjusted and optimized by seed layers with different materials.展开更多
Yttria (Y) dispersed ferrum (Fe) films were prepared by a double-target magnetron co-sputtering method. Vacuum annealing and xenon ion irradiation were conducted to investigate the influence on the magnetic and me...Yttria (Y) dispersed ferrum (Fe) films were prepared by a double-target magnetron co-sputtering method. Vacuum annealing and xenon ion irradiation were conducted to investigate the influence on the magnetic and mechanical properties of the films. The crystal grain growth mechanism and second phase precipitation mechanism were conducted simultaneously in the vacuum annealing process. These two effects led to an opposite variation of nano-hardness and coercivity in the films. Xenon ion irradiation played a role in rapid annealing, which also affected the magnetic performance of the yttria dispersed ferrum films.展开更多
Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency (RF) magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated....Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency (RF) magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sml films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi- tion temperatures.展开更多
This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that t...This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that the substrate temperature affects the surface morphology and magnetic property of CrAs thin film more potently than the thickness.展开更多
In order to improve the performances of electroplating permanent magnetic films, neodymium is introduced into the electroplating CoNiMnP permanent magnetic films. The influences of the neodymium content are also inves...In order to improve the performances of electroplating permanent magnetic films, neodymium is introduced into the electroplating CoNiMnP permanent magnetic films. The influences of the neodymium content are also investigated by varying NdCl3 plating bath concentration. The neodymium-doped films are analyzed by energy dispersive spectrum (EDS), vibrating sample magnetometer (VSM) and magnetic force microscope (MFM). The experimental results show that high magnetic performances of CoNdNiMnP permanent magnetic films with vertical anisotropy could be fabricated with current density 5mA/cm2 at room temperature. With the increasing of neodymium contents, the magnetic properties of films were improved. However when neodymium contents exceeded 3.5wt%, the magnetic properties of films are not improved any more. The increase of film magnetic properties results from the ferromagnetic-coupling between light rare earth element-neodymium and transition metal element-cobalt.展开更多
1 Results Nanoparticle media using arrays of monodisperse nanoparticles with high magneticanisotropy are assumed to be the ideal future magnetic recording media. However,key requirements like control of the magnetic a...1 Results Nanoparticle media using arrays of monodisperse nanoparticles with high magneticanisotropy are assumed to be the ideal future magnetic recording media. However,key requirements like control of the magnetic anisotropy orientation along with magnetic domain isolation have not been achieved so far. Here, we report on a combination of a two-dimensional topographic pattern formed of self-assembled nanoparticles with sizes as small as 20 nm and magnetic multilayer film deposition[1]. The so formed n...展开更多
Using Monte Carlo simulations, we have investigated the classical XY model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The int...Using Monte Carlo simulations, we have investigated the classical XY model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The internal energy, the specifc heat, the chirality and the chiral susceptibility are calculated in order to clarify phase transitions and critical phenomena. Prom the finite-size scaling analyses, the values of critical exponents are determined. In a range of interaction parameters, we find that the chirality steeply goes up as temperature increases in a temperature range; correspondingly the value of a critical exponent for this change is estimated.展开更多
The microwave permeability of laminated composites based on thin FeCoBSi films was under study.The level of permeability increased with increasing of the ferromagnetic inclusions in the laminates.The intrinsic permeab...The microwave permeability of laminated composites based on thin FeCoBSi films was under study.The level of permeability increased with increasing of the ferromagnetic inclusions in the laminates.The intrinsic permeability spectra of ferromagnetic inclusion are parametrically reconstructed.The obtained parameters of magnetic resonance were specially analyzed.To avoid the effect of eddy current and to obtain large-volume fractions of ferromagnetic constituent,laminates consisting of alternating FeCoBSi/SiO2 multi-layers and mylar substrates were also investigated.For the same volume fractions of ferromagnetic constituent (8.7%),laminates based on multi-layered films are found to possess higher values of permeability than those based on one-layered films.展开更多
Permeability characteristics of sputtered soft magnetic Fe40Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by a shortened microstrip transmission line perturbation method. Excellent microwave permea...Permeability characteristics of sputtered soft magnetic Fe40Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by a shortened microstrip transmission line perturbation method. Excellent microwave permeability is achieved at 0.4 Pa argon pressure: fr is 3.32 GHz, the real and imaginary part of permeability at 0.5 GHz are 104 and 61, respectively. In addition, the thickness effect on permeability is also studied. The minimum damping can be achieved at the thinnest film. Different sources contributed to in-plane anisotropy are discussed briefly. The deviation between the peak frequency of the imaginary part and the zero-crossing frequency of the real part of permeability is also presented.展开更多
Ag/[BN/CoPt]5/Ag and [BN/Ag/CoPt]5/Ag thin films were deposited on glass substrates by magnetron sputtering and then annealed in vac- uum at 600 ℃ for 30 min. The structures and magnetic properties of CoPt/BN multila...Ag/[BN/CoPt]5/Ag and [BN/Ag/CoPt]5/Ag thin films were deposited on glass substrates by magnetron sputtering and then annealed in vac- uum at 600 ℃ for 30 min. The structures and magnetic properties of CoPt/BN multilayer films were investigated as a function of Ag layer thickness. It was found that the face-centered tetragonal (fct) (001) texture of CoPt was improved greatly by introducing the Ag toplayer or sublayer together with an Ag underlayer. Good (001)-oriented growth, low intergrain interactions as well as high perpendicular anisotropy can be obtained in the Ag(3 nm)/[BN(2.5 nm)/CoPt(3 nm)]5/Ag(7 nm) and [BN(2.5 nm)/Ag(2 nm)/CoPt(3 nm)]5/Ag(10 nm) films, which become potential candidates for ultrahigh density magnetic recording media.展开更多
The change of conductivity, thickness and scanning electron microscopy (SEM) appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are inve...The change of conductivity, thickness and scanning electron microscopy (SEM) appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are investigated by testing film resistance, galvanostatic transient and using SEM to design magnetic circuit in magnetic assisted electrochemical machining (MAECM). The experiments show that the anode film has semi-conducting property. Compared with the situation without magnetic field applied, the resistance of the film formed at 1 .SV (anode potential) increased and decreased at 4.0V while B=0.4T and the magnetic north pole points toward anode. The SEM photo demonstrates that the magnetic field will densify the film in the passivation area and quicken dissolution of the anode metal in over-passivation area. Based on the influence of magnetic field on electrochemical machining(ECM) due to the changes of the anode film conductivity behavior, the magnetic north pole should be designed to point towards the workpiece surface that has been machined. Process experiments agree with the results of test analysis.展开更多
Yttrium iron garnet(YIG) films possessing both perpendicular magnetic anisotropy(PMA) and low damping would serve as ideal candidates for high-speed energy-efficient spintronic and magnonic devices.However,it is still...Yttrium iron garnet(YIG) films possessing both perpendicular magnetic anisotropy(PMA) and low damping would serve as ideal candidates for high-speed energy-efficient spintronic and magnonic devices.However,it is still challenging to achieve PMA in YIG films thicker than 20 nm,which is a major bottleneck for their development.In this work,we demonstrate that this problem can be solved by using substrates with moderate lattice mismatch with YIG so as to suppress the excessive strain-induced stress release as increasing the YIG thickness.After carefully optimizing the growth and annealing conditions,we have achieved out-of-plane spontaneous magnetization in YIG films grown on sGGG substrates,even when they are as thick as 50 nm.Furthermore,ferromagnetic resonance and spin pumping induced inverse spin Hall effect measurements further verify the good spin transparency at the surface of our YIG films.展开更多
Three kinds of oxide underlayers, namely Si02, ZnO and Al2O3, were deposited prior to the sputtering of Sr-ferrite films, respectively, in order to induce the optimum grain morphology and the texture of the films. A S...Three kinds of oxide underlayers, namely Si02, ZnO and Al2O3, were deposited prior to the sputtering of Sr-ferrite films, respectively, in order to induce the optimum grain morphology and the texture of the films. A Sr-ferrite film with an easy axis in-plane orientation was induced by SiO2 underlayer. In contrast, it prefers to be perpendicular to film plane for the cases of ZnO and Al2O3 underlayers. The optimum magnetic properties of the former film along film plane are: 4πMr=1.7 kG, iHc=5.35 kOe, and Sq=0.59, which are mainly dominated by the exchange coupling effect, determined by Wohlfarth's remanence analysis, among grains. While those for the films with an easy axis perpendicular to film plane can be as high as 4πMr=3.72 kG, iHc=6.42 kOe, and Sq=0.82, which are mainly dominated by the magnetostatic interaction among grains.展开更多
FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magn...FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%. The influences of texture, grain size, and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274321,11174302,11374312,and 11304326)the State Key Project of Fundamental Research of China(Grant Nos.2012CB933004 and 2009CB930803)+1 种基金the Ningbo Science and Technology Innovation Team(Grant Nos.2011B82004 and 2009B21005)the Ningbo Natural Science Foundations(Grant No.2013A610083)
文摘Flexible magnetic devices, i.e., magnetic devices fabricated on flexible substrates, are very attractive in applications such as detection of magnetic field in an arbitrary surface, non-contact actuators, and microwave devices, due to their stretchable, biocompatible, light-weight, portable, and low cost properties. Flexible magnetic films are essential for the realization of various functionalities of flexible magnetic devices. To give a comprehensive understanding for flexible magnetic films and related devices, recent advances in the study of flexible magnetic films are reviewed, including fabrication methods, magnetic and transport properties of flexible magnetic films, and their applications in magnetic sensors, actuators, and microwave devices. Our aim is to foster a comprehensive understanding of these films and devices. Three typical methods have been introduced to prepare the flexible magnetic films, by deposition of magnetic films on flexible substrates, by a transfer and bonding approach or by including and then removing sacrificial layers. Stretching or bending the magnetic films is a good way to apply mechanical strain to them, so that magnetic anisotropy, exchange bias, coercivity, and magnetoresistance can be effectively manipulated. Finally, a series of examples is shown to demonstrate the great potential of flexible magnetic films for future applications.
基金supported by the National Natural Science Foundation of China under grant No.19890310
文摘200 nm thick Fe-N magnetic thin films were deposited on glass substrates by RF sputtering. The as-deposited films have high saturation magnetization but their coercivity is also higher than what is needed Therefore it is very important to reduce coercivity. The samples were vacuum annealed at 250℃ under 12000 A/m magnetic field. When the N content was in the range of 5-7 at. pct, the thin films consisted of α' +α' after heat treatment and had excellent soft magnetic properties of 4πMs=2.4 T, HC <80 A/m. However, the thickness of a recording head was 2μm, and Hc increased as thickness increased. In order to reduce the Hc, the sputtering power was raised from 200 W to 1000 W to reduce the grain size. 2μm Fe-N thin films were vacuum annealed under the same condition, when the N content was in the range of 5.9-8.5 at. pct, the thin films kept its excellent magnetic properties of 4πMs=2.2 T, HC <80 A/m. The properties of the films meet the need of a recording head material used in the dual-element GMR/inductive heads.
基金the National Natural Science foundation of China under grant No.50572083.
文摘Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy, it has been found that the microstructure and the magnetic properties of films were influenced greatly by the bath pH. At the bath pH 8.06, the grain size and coercivity of the films reach maximuml while the squareness (Mr/Ms) of MH curves reaches minimum. The Henkel plots indicates that the exchange-coupling interaction is very weak at this pH, which may be caused by phase-separation and large grain size, and then results in the lowest squareness. At pH above 8.5, obvious exchange-coupling interaction is observed because of the inexistence of phase-separation and the refinement of grain size.
基金supported by the National Natural Science Foundation of China(Grant Nos 50371029 and 50771047)the Program for the New Century Excellent Talents in University of the Ministry of Education,China(Grant No NCET20420702)the Natural Science Foundation for the Distinguished Scholars of Hubei Province,China(Grant No 2005ABB002)
文摘A single layer of CoFeB and a multilayer of CoFeB MgO films are prepared by means of DC/RF magnetron sputter deposition. The excellent microwave properties and high electrical resistivity are simultaneously achieved in the discontinuous multilayer structure of [Co44Fe44B12(0.7nm)/MgO(0.4nm)]40 film. This film has a high permeability (μ′) (larger than 100 below 2.1 GHz), a high magnetic loss (μ″) (larger than 100 in a range from 1.5 to 3.3GHz), a resistivity of 3.3 × 10^3μΩ. cm, a saturation magnetization of 1.2 T, and an in-plane uniaxial anisotropy field of 5.5 kA/m. The microstructure and the surface topography of the film are also analysed. The relatively large surface roughness for the discontinuous film is responsible for the wide frequency band of magnetic loss. The magnetic loss and the high resistivity indicate that the discontinuous CoFeB MgO multilayer film has potential applications in microwave absorbers and electromagnetic interference (EMI) shielding materials in a GHz frequency range.
文摘It is proposed that the magnetization-induced anisotropy of magnetic films of cubic crystal structure originates from the anisotropy of atomic pair ordering, shape anisotropy, and strain anisotropy resulting from the constraint of the magnetostriction strain imposed on the film by the substratc. Calculated are the three anisotropy constants and their sum K vs temperature for Ni, Fe, and 55%Ni-Fe films; the room temperature (RT) constants vs the substrate temperature Tt during deposition or annealing after deposition for Ni and 50%Ni Co films; the RT constants vs com- position fraction for Fe-Ni films with Tt = RT, 250℃ and 450℃, Co Ni films at Tt = RT, 100℃ and 320℃, and Fe-Co films with Tt = RT and 300℃; the spread of RT K vs composition fraction for Fe Ni films; and RT △K/K vs composition fraction for Fe-Ni and Co Ni films, where △K denotes the variation of K of the film that is detached from its substrate. The calculated curves well accord with the measurements. The irrelevancy of K to the substrate material and the fast kinetics of the annealing in a field applied in the direction of the hard axis are explained reasonably.
基金Project supported by the Natural Science Foundation of Ningxia in China (Grant No.2022AAC03288)the Ningxia New Solid Electronic Materials and Devices Research and Development Innovation Team (Grant No.2020CXTDLX12)。
文摘The c-axis oriented hcp-Co_(81)Ir_(19)magnetic films were prepared on different seed layers(Ni,Cu,Ir,Pt,Au,and No seed).We systematically investigated the impact that surface-free energy and strain energy have on the orientation and defects and/or internal stress of the grains by increasing the lattice mismatch ratio.Moreover,the initial permeability and the natural resonance frequency were discussed in great detail using a comparison between calculated values and experimental values.We found that the almost unchanged 4πM_(s) andμ_(i) are not affected,while the changed H_(c),intrinsic K_(grain),and f_(r) are strongly dependent on the seed layer and seed layer material.Moreover,the extracted damping constant is sensitive to the defects and/or internal stress and orientation of the grains.Therefore,the soft magnetic properties and microwave properties are adjusted and optimized by seed layers with different materials.
基金support by the National Natural Science Foundation of China (No. 61076003)the National Basic Research and Development Program of China (Nos. 2010CB731600 and 2010CB832900)
文摘Yttria (Y) dispersed ferrum (Fe) films were prepared by a double-target magnetron co-sputtering method. Vacuum annealing and xenon ion irradiation were conducted to investigate the influence on the magnetic and mechanical properties of the films. The crystal grain growth mechanism and second phase precipitation mechanism were conducted simultaneously in the vacuum annealing process. These two effects led to an opposite variation of nano-hardness and coercivity in the films. Xenon ion irradiation played a role in rapid annealing, which also affected the magnetic performance of the yttria dispersed ferrum films.
基金supported by the National Natural Science Foundation of China (No. 61178067)the Natural Science Foundation of Shanxi Province, China (No.2010011032-1)+1 种基金the Graduate Innovation Fund of Shanxi Province, China (Grants No.20093096)the Taiyuan University Innovation and Entrepreneurship Thematic Projects (No. 100115154)
文摘Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency (RF) magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sml films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi- tion temperatures.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10334030, 10425419 and 60521001). Acknowledgments The authors acknowledge Professor Z.C. Niu, Professor F.H. Yang and Professor H.Z. Zheng for useful discussion.
文摘This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that the substrate temperature affects the surface morphology and magnetic property of CrAs thin film more potently than the thickness.
文摘In order to improve the performances of electroplating permanent magnetic films, neodymium is introduced into the electroplating CoNiMnP permanent magnetic films. The influences of the neodymium content are also investigated by varying NdCl3 plating bath concentration. The neodymium-doped films are analyzed by energy dispersive spectrum (EDS), vibrating sample magnetometer (VSM) and magnetic force microscope (MFM). The experimental results show that high magnetic performances of CoNdNiMnP permanent magnetic films with vertical anisotropy could be fabricated with current density 5mA/cm2 at room temperature. With the increasing of neodymium contents, the magnetic properties of films were improved. However when neodymium contents exceeded 3.5wt%, the magnetic properties of films are not improved any more. The increase of film magnetic properties results from the ferromagnetic-coupling between light rare earth element-neodymium and transition metal element-cobalt.
文摘1 Results Nanoparticle media using arrays of monodisperse nanoparticles with high magneticanisotropy are assumed to be the ideal future magnetic recording media. However,key requirements like control of the magnetic anisotropy orientation along with magnetic domain isolation have not been achieved so far. Here, we report on a combination of a two-dimensional topographic pattern formed of self-assembled nanoparticles with sizes as small as 20 nm and magnetic multilayer film deposition[1]. The so formed n...
基金Project supported by the National Natural Science Foundation of China (Grant No 10234010), Acknowledgements The authors would like to thank Professor T. Horiguch for his useful discussion. 0ur simulations were carried out on IBM RS/6000 SP3 at the Centre for Computational Science and Engineering of Peking University.
文摘Using Monte Carlo simulations, we have investigated the classical XY model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The internal energy, the specifc heat, the chirality and the chiral susceptibility are calculated in order to clarify phase transitions and critical phenomena. Prom the finite-size scaling analyses, the values of critical exponents are determined. In a range of interaction parameters, we find that the chirality steeply goes up as temperature increases in a temperature range; correspondingly the value of a critical exponent for this change is estimated.
基金Funded by the National Natural Science Foundation of China(Nos.60701016,60911130130)the Fundamental Research Funds for the Central Universities (No.ZYGX2009J032)
文摘The microwave permeability of laminated composites based on thin FeCoBSi films was under study.The level of permeability increased with increasing of the ferromagnetic inclusions in the laminates.The intrinsic permeability spectra of ferromagnetic inclusion are parametrically reconstructed.The obtained parameters of magnetic resonance were specially analyzed.To avoid the effect of eddy current and to obtain large-volume fractions of ferromagnetic constituent,laminates consisting of alternating FeCoBSi/SiO2 multi-layers and mylar substrates were also investigated.For the same volume fractions of ferromagnetic constituent (8.7%),laminates based on multi-layered films are found to possess higher values of permeability than those based on one-layered films.
文摘Permeability characteristics of sputtered soft magnetic Fe40Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by a shortened microstrip transmission line perturbation method. Excellent microwave permeability is achieved at 0.4 Pa argon pressure: fr is 3.32 GHz, the real and imaginary part of permeability at 0.5 GHz are 104 and 61, respectively. In addition, the thickness effect on permeability is also studied. The minimum damping can be achieved at the thinnest film. Different sources contributed to in-plane anisotropy are discussed briefly. The deviation between the peak frequency of the imaginary part and the zero-crossing frequency of the real part of permeability is also presented.
基金supported by the National Natural Science Foundation of China (No.10574085)the Scientific Research of Yuncheng University,China (No.2009007)
文摘Ag/[BN/CoPt]5/Ag and [BN/Ag/CoPt]5/Ag thin films were deposited on glass substrates by magnetron sputtering and then annealed in vac- uum at 600 ℃ for 30 min. The structures and magnetic properties of CoPt/BN multilayer films were investigated as a function of Ag layer thickness. It was found that the face-centered tetragonal (fct) (001) texture of CoPt was improved greatly by introducing the Ag toplayer or sublayer together with an Ag underlayer. Good (001)-oriented growth, low intergrain interactions as well as high perpendicular anisotropy can be obtained in the Ag(3 nm)/[BN(2.5 nm)/CoPt(3 nm)]5/Ag(7 nm) and [BN(2.5 nm)/Ag(2 nm)/CoPt(3 nm)]5/Ag(10 nm) films, which become potential candidates for ultrahigh density magnetic recording media.
基金National Defense Foundation of China (No.51318030401).
文摘The change of conductivity, thickness and scanning electron microscopy (SEM) appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are investigated by testing film resistance, galvanostatic transient and using SEM to design magnetic circuit in magnetic assisted electrochemical machining (MAECM). The experiments show that the anode film has semi-conducting property. Compared with the situation without magnetic field applied, the resistance of the film formed at 1 .SV (anode potential) increased and decreased at 4.0V while B=0.4T and the magnetic north pole points toward anode. The SEM photo demonstrates that the magnetic field will densify the film in the passivation area and quicken dissolution of the anode metal in over-passivation area. Based on the influence of magnetic field on electrochemical machining(ECM) due to the changes of the anode film conductivity behavior, the magnetic north pole should be designed to point towards the workpiece surface that has been machined. Process experiments agree with the results of test analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.52072060 and 52021001)the National Key R&D Program of China(Grant No.2021YFB2801600)the China Postdoctoral Science Foundation(Grant No.2021M700679)。
文摘Yttrium iron garnet(YIG) films possessing both perpendicular magnetic anisotropy(PMA) and low damping would serve as ideal candidates for high-speed energy-efficient spintronic and magnonic devices.However,it is still challenging to achieve PMA in YIG films thicker than 20 nm,which is a major bottleneck for their development.In this work,we demonstrate that this problem can be solved by using substrates with moderate lattice mismatch with YIG so as to suppress the excessive strain-induced stress release as increasing the YIG thickness.After carefully optimizing the growth and annealing conditions,we have achieved out-of-plane spontaneous magnetization in YIG films grown on sGGG substrates,even when they are as thick as 50 nm.Furthermore,ferromagnetic resonance and spin pumping induced inverse spin Hall effect measurements further verify the good spin transparency at the surface of our YIG films.
文摘Three kinds of oxide underlayers, namely Si02, ZnO and Al2O3, were deposited prior to the sputtering of Sr-ferrite films, respectively, in order to induce the optimum grain morphology and the texture of the films. A Sr-ferrite film with an easy axis in-plane orientation was induced by SiO2 underlayer. In contrast, it prefers to be perpendicular to film plane for the cases of ZnO and Al2O3 underlayers. The optimum magnetic properties of the former film along film plane are: 4πMr=1.7 kG, iHc=5.35 kOe, and Sq=0.59, which are mainly dominated by the exchange coupling effect, determined by Wohlfarth's remanence analysis, among grains. While those for the films with an easy axis perpendicular to film plane can be as high as 4πMr=3.72 kG, iHc=6.42 kOe, and Sq=0.82, which are mainly dominated by the magnetostatic interaction among grains.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874060 and 60803035)
文摘FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%. The influences of texture, grain size, and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.