共查询到19条相似文献,搜索用时 218 毫秒
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采用磁控溅射方法制备了以Pt为缓冲层和保护层的具有垂直各向异性(Pt/Co)n/ FeMn多层膜.研究结果表明,多层膜的垂直交换偏置场Hex和反铁磁层厚度的关 系与其具有平面各向异性的交换偏置场随反铁磁层厚度变化趋势相近.随着铁磁层调制周期 数的增加,垂直交换偏置场Hex相应减小,并且与铁磁层的调制周期数近似成反 比关系.(Pt/Co)3/FeMn的垂直交换偏置场Hex已经达到22.3kA/m.为
关键词:
交换偏置
垂直各向异性
多层膜 相似文献
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利用磁控溅射法制备了Nd28Fe66B6/Fe50Co50 双层纳米复合磁性薄膜,研究了其结构和磁性.经873K退火处理15min 后,利用x射线衍射仪测定薄膜晶体结构,采用俄歇电子能谱仪估算薄膜厚度和超导量子干 涉仪测量其磁性.磁性测量表明,1)该系列薄膜具有垂直于膜面的磁各向异性.从起始磁化曲 线和小回线的形状特征可知,矫顽力机制主要是由畴壁钉扎控制.2)对于固定厚度(10nm) 层的硬磁相Nd-Fe-B和不同厚度(dFeCo=1—100nm)层软磁相FeCo双层纳米复合 膜,剩磁随软磁相FeCo 厚度的增加快速增加,而矫顽力则减少.当dFeCo=5nm 时 ,最大磁能积达到160×103A/m.磁滞回线的单一硬磁相特征说明,硬磁相Nd -Fe-B层和软磁相FeCo层之间的相互作用使两相很好地耦合在一起.剩磁和磁能积的提高是由 于两相磁性交换耦合所致.
关键词:
Nd-Fe-B/FeCo双层纳米复合膜
交换耦合
磁性增强 相似文献
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利用电弧炉熔炼了Ni50Mn35In15多晶样品,根据磁性测量对其马氏体相变和磁热效应进行了系统研究.结果表明,随着温度的降低,样品在室温附近先后发生了二级磁相变与一级结构相变特征的马氏体相变,导致它的磁化强度产生突变. 同时通过低温下的磁滞回线的测量发现样品存在交换偏置行为,表明低温下马氏体相中铁磁和反铁磁共存. 此外,根据Maxwell方程,计算了样品在马氏体相变温度附近的磁熵变,当温度为309K,磁场改变5 T时,样品的磁熵变可达22.3J/kgK.
关键词:
哈斯勒合金
50Mn35In15')" href="#">Ni50Mn35In15
马氏体相变
磁热效应 相似文献
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研究铁磁/反铁磁双层膜系统中交换偏置场和矫顽场的冷却磁场依赖性.结果表明,随着冷却磁场的增加,交换偏置场由负值向正值转变.在转变点附近,矫顽场有-个特别的增强,并达到最大值.结果同相关实验-致.研究铁磁层和反铁磁层厚度对交换偏置场和矫顽场的影响.发现,正负交换偏置场和矫顽场随着铁磁层厚度的增大而减小,但随反铁磁层厚度的变化关系复杂.在正交换偏置场的情形,随反铁磁层厚度的增大,交换偏置场增强,矫顽场减弱;在负交换偏置场的情形,随反铁磁层厚度的增大,交换偏置场减弱,矫顽场增强. 相似文献
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采用磁控溅射方法制备了以Pt为缓冲层和保护层的具有垂直各向异性(Pt/Co)n/FeMn多层膜.研究结果表明,多层膜的垂直交换偏置场Hex和反铁磁层厚度的关系与其具有平面各向异性的交换偏置场随反铁磁层厚度变化趋势相近.随着铁磁层调制周期数的增加,垂直交换偏置场Hex相应减小,并且与铁磁层的调制周期数近似成反比关系.(Pt/Co)3/FeMn的垂直交换偏置场Hex已经达到22.3kA/m.为了进一步提高Hex,在Co/FeMn的界面插入Pt层,当Pt层厚度为0.4nm时,Hex达到最大值39.8kA/m. 相似文献
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从理论和实验上对Fe/MnPd薄膜的交换偏置效应、各向异性和矫顽力的增加作了系统的研究.研究表明,在FM/AF结构中,FM和AF的交换耦合作用会诱导系统产生高阶各向异性,在Fe/MnPd结构中获得的单轴和立方各向异性的大小同单轴各向异性与铁磁层的厚度成反比关系一样.同时,铁磁层(FM)和反铁磁层(AF)的交换耦合作用诱导而产生的高阶各向异性的存在是使系统矫顽力增加的重要原因.
关键词: 相似文献
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研究了磁场诱导生长的BiFeO3/Ni18Fe19磁性双层膜中 的交换偏置及其热稳定性. 结果表明: BiFeO3/Ni18Fe19双层膜中的交换偏置场Hex未表现出明显的磁练习效应. 在负饱和磁场等待过程中, BiFeO3/Ni18Fe19双层膜磁滞回线的前支和后支曲 线都随着在负饱和磁场中等待时间tsat的增加向正场方向偏移. 交换偏置场Hex的大小随着等待时间tsat的增加而减小, 矫顽力Hc基本不变. 交换偏置场Hex的大小随测量温度Tm的升高变化不明显, 表现出良好的热稳定性; 但矫顽力Hc随Tm的升高而显著减小. 良好的热稳定性应该来源于铁电性和反铁磁性间的共同耦合作用.
关键词:
多铁性
磁性薄膜
交换偏置
热稳定性 相似文献
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J.J. Qiu K.B. Li G.C. Han Y.K. Zheng Z.B. Guo Y.H. Wu 《Journal of magnetism and magnetic materials》2006
The influence of deposition power and seedlayer on the properties of hard magnet Co50Pt50 was studied. Co50Pt50(/Co90Fe10)/Ru/Co90Fe10 trilayer was used as pining/pinned layer in spin valves. The influences of different hard layer, soft layer and free layer on exchange bias, interlayer coupling, and magnetoresistance (MR) ratio were studied. Weak antiferromagnetic interlayer coupling was obtained by adjusting the thickness of hard and soft layers. MR of a spin valve with structure Cr2/CoFe0.5/CoPt4/CoFe0.5/Ru0.8/CoFe2.2/Cu2.05/CoFe2.6/Cu1.1/Ta1 reached 10.68% (unit in nm), which is comparable to those of IrMn-based synthetic spin valves. The increment of the coercivity of the free layer is mainly due to the static magnetic interaction between the hard layer and the free layer. 相似文献
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Ba0.6Sr0.4TiO3 thin films were deposited on Pt/SiO2/Si substrate by radio frequency magnetron sputtering. High-resolution transmission electron microscopy (HRTEM) observation shows that there is a transition layer at BST/Pt interface, and the layer is about 7-8 nm thickness. It is found that the transition layer was diminished to about 2-3 nm thickness by reducing the initial RF sputtering power. X-ray photoelectron spectroscopy (XPS) depth profiles show that high Ti atomic concentration results in a thick interfacial transition layer. Moreover, the symmetry ν of ?r-V curve of BST thin film is enhanced from 52.37 to 95.98%. Meanwhile, the tunability, difference of negative and positive remanent polarization (Pr), and that of coercive field (EC) are remarkably improved. 相似文献
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通过调整Mn的成分,系统地研究了Ni81Fe19/Ni100-xMnx双层膜的磁学性质,特别是交换偏置场(Hex)的变化.当Ni100-xMnx中Mn的原子百分比在534%到600%之间时,对于150nm的Ni81Fe19,得到了最大的交换偏置场175kA/m,同时由于Mn对Ni81Fe19层的扩散所造成的磁矩的降低小于20%;高角x射线衍射证明Ni100-xMnx的晶格常数随着Mn成分的改变而变化,Mn含量越多,其晶格常数越大;制备态Ni100-xMnx膜晶格常数与θ相NiMn膜晶格常数的接近程度与NiMn膜θ相形成的容易程度相对应.也研究了交换偏置场随着Ni100-xMnx厚度的变化,第一次得到了当Ni100-xMnx中Mn的原子百分比为706%时,Ni81Fe19(150nm)/Ni100-xMnx(90nm)双层膜在经过240℃,5h退火后,可以有80kA/m的交换偏置场,此时铁磁层磁矩的大小几乎不变.
关键词:
Ni81Fe19/Ni100-xMnx
交换偏置场 相似文献
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Jun Wan Yunhe Huang Chaoying Ni 《Journal of magnetism and magnetic materials》2010,322(13):1811-10574
Exchange coupling between hard and soft magnetic materials has implications for both permanent magnet and magnetic recording technologies. This paper looks at exchange coupling of FCC FePt epitaxially grown onto (0 0 1) oriented L10 FePt deposited on (0 0 1) MgO substrates at elevated temperature. By varying the thickness of the FCC layer there is a relaxation of the single crystal FCC layer that produces a polycrystalline microstructure as evidenced by the development of rings in the electron diffraction pattern. A concurrent decoupling of the layers is apparent from magnetization curves with two distinct switching fields as the FCC layer thickness is increased above 20 nm. The results shown here confirm the importance of the epitaxial relationship between materials of disparate anisotropies in maintaining strong exchange coupling. 相似文献
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The value of the effective magnetic anisotropy constant of the ferrimagnetic nanoparticles Zn0.15Ni0.85Fe2O4 embedded in a SiO2 silica matrix, determined through ferromagnetic resonance (FMR), is much higher than the magnetocrystalline anisotropy constant. The higher value of the anisotropy constant is due to the existence of surface anisotropy. However, even if the magnetic anisotropy is high, the ferrimagnetic nanoparticles with a 15% concentration, which are isolated in a SiO2 matrix, display a superparamagnetic (SPM) behavior at room temperature and at a frequency of the magnetization field equal to 50 Hz. The FMR spectrum of the novel nanocomposite (Zn0.15Ni0.85Fe2O4)0.15/(SiO2)0.85, recorded at room temperature and a frequency of 9.060 GHz, is observed at a resonance field (B0r) of 0.2285 T, which is substantially lower than the field corresponding to free electron resonance (ESR) (0.3236 T). Apart from the line corresponding to the resonance of the nanoparticle system, the spectrum also contains an additional weaker line, identified for a resonance field of ∼0.12 T, which is appreciably lower than B0r. This line was attributed to magnetic ions complex that is in a disordered structure in the layer that has an average thickness of 1.4 nm, this layer being situated on the surface of the Zn0.15Ni0.85Fe2O4 nanoparticles that have a mean magnetic diameter of 8.9 nm. 相似文献
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《Journal of magnetism and magnetic materials》2001,224(1):61-64
Ta/NiO/NiFe/Ta multilayers, utilizing Ta as the buffer layer, were prepared by RF reactive and DC magnetron sputtering. The exchange coupling field between NiO and NiFe reached a maximum value of 120 Oe at a NiO film thickness of 50 nm. The composition and chemical state at the interface region of Ta/NiO/Ta were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an `intermixing layer’ at the Ta/NiO (and NiO/Ta) interface due to a thermodynamically favorable reaction: 2Ta+5NiO=5Ni+Ta2O5. This interface reaction has an effect on the exchange coupling. The thickness of the `intermixing layer’ as estimated by XPS depth-profiles was about 8–10 nm. 相似文献
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从Landau-Devonshire唯象理论出发,考虑到晶格失配导致的NFDA3位错应力场与极化场的耦合,研究了在SrTiO3衬底上外延生长的PbZr0.4Ti0.6O3薄膜厚度对其自发极化强度、电滞回线的影响. 结果表明,产生刃位错的PbZr0.4Ti0.6O3薄膜临界厚度为~1.27nm,当薄膜厚度大于临界厚度时,在所形成的位错附近,极化强度出现急剧变化,形成自发极化强度明显减弱的“死层”;随着薄膜厚度的减小,位错间距增大,“死层”厚度与薄膜总厚度之比增加. 由薄膜电滞回线的变化情况可知,其剩余极化强度随着薄膜厚度的减小而逐渐减小.
关键词:
铁电薄膜
自发极化强度
电滞回线
位错 相似文献
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The reflection properties of planar anisotropy Fe50Ni50 powder/paraffin composites have been studied in the microwave frequency range. The permeability of Fe50Ni50 powder/paraffin composites is greatly enhanced by introducing the planar anisotropy, and can be further enhanced by using a rotational orientation method. The complex permeability can be considered as the superposition of two types of magnetic resonance. The resonance peak at high frequency is attributed to the natural resonance, while the peak at low frequency is attributed to the domain-wall resonance. The simulated results of the microwave reflectivity show that the matching thickness, peak frequency, permeability, and permittivity are closely related to the quarter wavelength matching condition. The Fe50Ni50 powder/paraffin composites can be attractive candidates for thinner microwave absorbers in the L-band (1-2 GHz). 相似文献