共查询到19条相似文献,搜索用时 140 毫秒
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本文研究了Pd2Si的生成对周期性Pd/Si多层膜X射线衍射性能的影响。X射线衍射强度的测量数据表明Pd2Si的生成对长周期多层膜的衍射强度影响不大,但对短周期多层膜衍射强度的影响较大。在引入折射率修正后,我们不仅用单个峰的位置计算了多层膜的周期,而且还用了以两个峰的位置联立消去折射率修正的方法计算了多层膜的周期,前者的误差大于后者。模拟计算的结果说明:均匀Pd2Si层的生成不足以解释Pd/Si多层膜衍射强度随退火温度的变化,界面的平整化或粗糙化是影响衍射强度的另一个要素。
关键词: 相似文献
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用直流磁控溅射法在Si(001)衬底上制备了以Ta为缓冲层、含有15周期的Ni80Fe20(4nm)/Cu(6nm)多层膜.样品分别在150,250,350℃进行了真空退火处理.用低角和高角X射线衍射法研究了多层膜的微结构.结果表明,所有样品均有较好的[111] 取向,而且随退火温度或时间的增加,[111]取向程度变得更高.超晶格周期、平均面间距在退火后略有减小,表明多层膜结构在退火后变得更为致密.多层膜界面粗糙度随退火温度或时间的增加而增大,平均相关长度随退火温度或时间的增加而减小,分析认为这是由于Ni80Fe20/Cu界面存在严重的互扩散所导致的.模拟Ni80Fe20/Cu多层膜高角X射线衍射谱,发现在Ni80Fe20/Cu蜀面有非常厚的混合层存在,而且混合层厚度随退火温度或时间的增加而增大.模拟结果还表明,随退火温度或时间的增加,Ni80Fe20层面间距几乎保持不变,Cu层面间距则随退火温度的增加而略有减小.
关键词: 相似文献
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讨论了利用分子场近似结合中子衍射或X射线衍射的实验结果计算R2Fe17型稀土过渡族化合物中稀土磁矩与过渡族磁矩之间交换耦合常量的方法,并据此计算了R2Fe17-xAlx(R=Tb,Dy,Ho,Er,Gd,x=7或8)化合物中稀土磁矩与过渡族磁矩之间的交换耦合常量.计算结果与实验值符合较好.
关键词:
2Fe17-xAlx化合物')" href="#">R2Fe17-xAlx化合物
交换耦合常量 相似文献
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基于第一性原理投影缀加波和梯度矫正局域密度近似(PAW-GGA), 研究了Nd2Fe14B和Dy2Fe14B的基态晶格属性, 进而对Dy在Nd2Fe14B晶格中的掺杂进行了研究, 并采用GGA+U的方式进行了原子磁矩计算, 并与自旋轨道耦合 (SOI) 计算结果进行了对照. 置换计算表明, Dy原子倾向于置换Nd2Fe14B晶格中4f位的稀土原子. 磁矩计算表明, 在R2Fe14B (R: 稀土元素) 晶格中, 4f位的稀土元素与Fe原子作用更强, 对磁性能的影响更大. 稀土原子与Fe的作用与距离呈正相关.
关键词:
2Fe14B')" href="#">Nd2Fe14B
晶格占位
形成能
原子磁矩 相似文献
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制备了Nd28Fe66B6/Fe50Co50多层纳米复合磁性薄膜,对溅射态和650℃退火处理15 min试样的相成分分析和微结构的观察显示,溅射态薄膜呈非晶态,经650℃退火处理15 min后,薄膜主要相成分为硬磁性Nd2Fe14B相和软磁性相FeCo(110)相.Nd2Fe14B相呈柱状,其易磁化c轴垂直于膜面,尺寸约10 nm.在硬磁性相和软磁性相之间存在少量富Nd相和非晶态,富Nd相大小约7 nm.磁性测量和分析表明,1)该系列薄膜退火态具有垂直于膜面的磁晶各向异性.2)对于固定厚度(10 nm)层Nd-Fe-B和不同厚度(tFeCo=1—100 nm)层FeCo多层纳米复合膜,剩磁随软磁相FeCo 厚度的增加快速增加,而矫顽力则减小.当tFeCo=5 nm时,最大磁能积达到200 kJ/m3. 3)硬磁相Nd-Fe-B层和软磁相FeCo层之间交换耦合导致剩磁和磁能积增强.
关键词:
Nd-Fe-B/FeCo多层纳米复合膜
交换耦合
磁各向异性 相似文献
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采用基于密度泛函理论的投影缀加波方法研究了Heusler合金Pd2CrAl的四方变形、磁性和弹性常数. 四方变形中,Pd2CrAl在c/a≈1.20处出现总能的局域最小值,对应一个稳定的马氏体. Pd2CrAl的L21结构和四方结构的单胞总磁矩分别为3.825μB和3.512μB. 在这两种结构中Cr原子均是Pd2CrAl总磁矩的主要贡献者,Pd和Cr原子间存在很强的杂化作用,Cr的3d电子的t2g和eg两个亚能带是Pd2CrAl磁性的主要来源. 弹性常数的计算结果显示,Pd2CrAl的L21结构和四方结构的弹性常数均满足相应结构的稳定性判据.
关键词:
Heusler合金
四方变形
磁性
弹性常数 相似文献
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对以本征Si及重掺杂p型和n型Si作为中间层的Fe/Si多层膜的层间耦合进行研究,并通过退火,增大Fe,Si之间的扩散,分析界面扩散对层间耦合的影响. 实验结果表明,层状结构良好的制备态的多层膜,Fe,Si之间也存在一定程度的扩散,它是影响层间耦合的 主要因素,远远超过了半导体意义上的重掺杂,使不同种类的Si作为中间层的层间耦合基本 一致.进一步还发现,在一定范围内增大Fe,Si之间的扩散,即使多层膜的层状结构已经有了相当的退化,Fe/Si多层膜的反铁磁耦合强度基本保持不变.
关键词:
Fe/Si多层膜
层间耦合
界面扩散 相似文献
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《Journal of magnetism and magnetic materials》1999,192(3):423-430
Polycrystalline (Fe/Pd)n multilayers are grown onto sapphire substrates at room temperature in a UHV system. The number of periods n=40 and the thickness of Pd layers of tPd=4 nm are kept constant, whereas the thickness of the Fe layers is varied from 1.5 to 5 nm. Structural properties are studied by in situ reflection high energy diffraction (RHEED), scanning tunnelling microscopy (STM) and ex situ by X-ray diffraction at small angles and large angles. Analyzing the experimental data using the program SUPREX we obtain interplanar distances of dFe=2.03±0.01 Å for an Fe layer thickness larger than about 2.5 nm as expected for (1 1 0) planes of BCC Fe. For Fe layers with thicknesses less than about 2.5 nm the interplanar distance is dFe=2.1±0.01 Å, which is close to the distance between (1 1 1) planes of FCC Fe with a lattice parameter of a=3.64 Å. Magnetic susceptibility measurements at temperatures between 1.5 and 300 K for (Fe/Pd)n multilayers with FCC Fe yield a magnetic moment per Fe atom of μ=2.7±0.1 μB, which is about 20% larger compared to μ=2.2 μB for BCC Fe. We show that the occurrence of the large magnetic moment originates from FCC Fe being in the high spin (HS) state rather than from polarization effects of Pd at Fe/Pd interfaces. 相似文献
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利用电化学沉积方法在氧化铝模板中制备了一维Fe和Fe095Pd0 05合金纳米线阵列.两种样品均有(110)晶向择优取向,纳米线直径为60nm.在这一直径下形状各向异性 和内禀晶体各向异性的竞争结果很适合考察Pd掺杂的磁性行为.研究发现在FePd纳米线中, 由于极少量Pd在Fe中的合金化,减弱了晶体各向异性与形状各向异性的影响,改变了磁畴结 构,增强了畴壁钉扎作用,结果在Fe095Pd005纳米线 中便显示出强烈的沿线方向的各向异性,方形度和矫顽力也有较大改善.
关键词:
纳米线
电化学沉积
磁性 相似文献
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L. S. Uspenskaya A. L. Rakhmanov L. A. Dorosinskii A. A. Chugunov V. S. Stolyarov O. V. Skryabina S. V. Egorov 《JETP Letters》2013,97(3):155-158
The magnetic properties of hybrid thin-film Pd0.99Fe0.01-Nb structures are studied by a magneto-optical technique. It is shown that, below 14 K, the samples exhibit the ferromagnetic ordering corresponding to the formation of weakly coupled ferromagnetic nanoclusters. In the clusters, the effective spin polarization of Fe ions is about 4μB, corresponding to that in the bulk Pd3Fe alloy. The proximity of the ferromagnetic layer does not suppress the superconductivity in niobium. It does not affect the superconducting transition temperature but leads to an enhanced pinning and results in an increase in the critical current by about 30%. This behavior agrees well with the existence of the nanocluster structure in the ferromagnetic film. 相似文献
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N. I. Plyusnin V. M. Il’yashchenko S. A. Kitan’ W. -Ch. Lin Ch. -Ch. Kuo 《Technical Physics》2014,59(7):1017-1026
The growth of a Fe sublayer 1.5–14.0 monolayers (MLs) thick and a Cu film (about 5 MLs) on this sublayer is studied at a reduced temperature (1240°C) and an elevated temperature (1400°C) of a Fe source and at a reduced temperature (900°C) of a Cu source. The films are examined by Auger electron spectroscopy, low-energy electron diffraction, and atomic force microscopy. As metal sources, thin Fe and Cu strips on a Ta foil are used. It is shown that a nonequilibrium 2D phase forms in the Fe-on-Si(001) film up to a thickness of 4–5 MLs. This phase appears as closely packed atomically smooth nanoislands. When the thickness of the film exceeds 4–5 MLs, the nonequilibrium Fe phase changes to the bulk (3D) phase of Fe and its silicide Fe x Si. At Fe source temperatures of 1240 and 1400°C, the nonequilibrium phase consists of Fe with Si segregated on the Fe surface, and a Fe-Si mixture. Copper on the nonequilibrium Fe and Fe-Si phases grows, respectively, as a smooth layer Cu with Si segregated on the top and in the form of Cu-Fe and Cu-Si mixtures. Cu islands growing on the bulk Fe and Fe x Si phases have smaller and larger sizes, respectively. 相似文献
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I. A. Garifullin D. A. Tikhonov N. N. Garif’yanov M. Z. Fattakhov K. Theis-Bröhl K. Westerholt H. Zabel 《Applied magnetic resonance》2002,22(3):439-452
Epitaxial V/Pd1−x Fe x (001) bilayers with a V thickness of the order of 40 nm and with a Pd1−x Fe x thickness in the range from 0.8 nm to 4.4 nm were prepared by molecular beam epitaxy techniques. The Curie temperature of the Pd1−x Fe x layers varies between 90 and 250 K. For a bilayer with a Pd1−x Fe x thickness of 1.2 nm the ferromagnetic resonance measurements revealed a decrease of the effective magnetization 4πM eff of the ferromagnetic layer below the superconducting transition temperature of V. As a possible explanation for this decrease we suggest a spatial modulation of the ferromagnetic order in the Pd1−x Fe x layer due to modifications of the indirect exchange interaction of magnetic ions via conduction electrons in the superconducting state. A comparison with a recent theoretical investigation supports this possibility. 相似文献
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MAGNETIC POLARIZATION OF Pd SPACERS AND OSCILLATORY EXCHANGE COUPLING BETWEEN Fe AND Pd LAYERS IN Fe/Pd MULTILAYERS 下载免费PDF全文
Ay oscillatory behavior in specific saturation magnetization of Fe/Pd multilayers is observed. The conversion electron M?ssbauer spectroscopy and other experiments indicate that this behavior is caused by the magnetic polarization of Pd spacers, which alternates between positive and negative polarization with respect to the magnetic moments of Fe layers. The interlayer coupling between two Fe layers always keeps ferromagnetic. Then, the interlayer couplings in ferromagnetic metal/nearly ferromagnetic metal multilayers were calculated By using the model of Barnas. The results of calculation prove that the above phenomenon might appear under some condition. The influence of magnetic polarization potential of spacers and interface chemical potential on the interlayer couplings is also discussed. 相似文献
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N. B. Bakulina M. I. Kurkin S. A. Gudin A. V. Gapontsev 《Physics of the Solid State》2010,52(2):328-334
The possibility of appearing jumps in the magnetization curves of Fe/Cr multilayers has been predicted under the assumption
that magnetic ordering in chromium interlayers has the form of a linearly polarized spin-density wave. This possibility has
been analyz ed for an Fe/Cr/Fe three4ayer film with a conventional quality of Fe/Cr interfaces, which does not ensure a change
in the ferromagnetic and antiferromagnetic orientations of the magnetizations of neighboring iron layers with a variation
in the thickness of the chromium interlayer by one atomic layer (short oscillation period). The model used suggests that the
wave vector of the spin-density wave is responsible for the experime ntally observed long period of these oscillations. Relationships
have been derived for the range of thicknesses of chromium interlayers in which the appearance of the predicted effect can
be expected, and the magnitude of the effect has been evaluated. 相似文献
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Pd and Fe exchanged NaX and NaZSM-5 catalysts (Pd/Fe=5) were studied. The components formed in the course of hydrogen activation
at 720 K and their transformations taking place during treatments in CO+H2 at 570 and 500 K are described. PdxFe, Fe2+ ions in octahedral and tetrahedral environments and x-iron carbide components are identified. The bimetallic component is
not affected by the CO+H2 treatment. The Fe2+ ions located only in tetrahedral environment were transformed into iron carbide in the X zeolite framework, while the Fe2+ ions of octahedral environment were also transformed in part to carbide in the ZSM-5 lattice. 相似文献