共查询到18条相似文献,搜索用时 78 毫秒
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在一维海森堡模型的基础上,采用界面参数化方法,将双层异质磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程.重点讨论体系中体模和完全禁闭模的波形演化过程,发现体系中体模波形随自旋波矢呈余弦变化,会出现局域共振现象.激发能对两子层中体模有较大的影响,不仅影响体模的振幅,而且还影响体模的波长.另外,激发能对体系中的完全禁闭模也有较大影响,随着激发能增大,铁磁层中完全禁闭模波长变短,波速变小,但振幅不变. 相似文献
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在海森堡模型的基础上,采用界面参数化方法,将双层铁磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程.重点研究了界面各向异性对薄膜中自旋波本征问题的影响.结果表明:界面各向异性使对称模的波形在界面处呈现明显的钉扎现象,且界面模的能量随各向异性场增强而增大. 相似文献
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磁性斯格明子由于具有拓扑保护、尺寸小、驱动电流密度低等优异的属性,有望作为未来超高密度磁存储和逻辑功能器件的信息载体.为了满足器件中信息写入和读取的基本要求,需要在室温下实现斯格明子的精确产生、操控和探测.该综述简要介绍最近我们针对上述问题取得的一系列研究进展,包括:1)证明可以通过控制磁性薄膜材料的垂直磁各向异性在室温下产生斯格明子,并进一步在基于反铁磁的薄膜异质结中发现了室温、零磁场下稳定存在的斯格明子;2)证明能够利用电流产生的自旋轨道力矩操控斯格明子,并进一步制备出一种基于斯格明子的原理型器件,实现了利用电学方式产生和操控数量可控的斯格明子. 相似文献
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本文在一维海森堡模型的基础上,采用界面参数化方法,研究了铁磁/反铁磁双层薄膜中自旋波低温激发问题.重点讨论了表面各向异性对薄膜中自旋波共振谱的影响.结果表明:体系中的自旋波本征模存在共振行为,表面各向异性场对体模、完全禁闭模的共振谱影响较大,对界面模没有影响. 相似文献
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本文在一维海森堡模型的基础上,采用界面参数化方法,研究了铁磁/反铁磁双层薄膜中自旋波低温激发问题.重点讨论了表面各向异性对薄膜中自旋波共振谱的影响.结果表明:体系中的自旋波本征模存在共振行为,表面各向异性场对体模、完全禁闭模的共振谱影响较大,对界面模没有影响. 相似文献
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通过求解磁性d波超导中的能隙与磁交换能的自恰方程,利用推广的Blonder-Tinkham-Klapwijk 理论研究磁性半导体/磁性d波超导结中自旋极化准粒子输运系数与微分电导. 计算表明: 1) 磁性d波超导结中的磁交换能h0可导致零偏压电导峰与能隙电导峰劈裂,劈裂的宽度为2h0;2) 磁性半导体中的磁交换能hFS可使零偏压电导峰劈裂的峰值变低. 而由能隙电导峰劈裂的两个子峰,当两种磁性材料的磁
关键词:
磁性半导体
磁性d波超导体
自旋极化输运 相似文献
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Ferromagnetic resonance is introduced to examine the microwave frequency response of Ni Fe/Ir Mn bilayers, patterned as antidot arrays. In the experiment, field direction dependence on mode is obtained by rotating the applied magnetic field. We find that at a given resonance frequency, the dependence of the resonance field on the angle has a tendency of sinusoid/cosine variation in the experiment. From micromagnetic simulation it can be seen that spin waves are localized between dots from a given mode profile. This is caused by a demagnetization distribution with a larger value in the center of the two nearest dots than that of the next-nearest dots. 相似文献
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The eigenproblems of spin waves in a symmetrical
ferromagnetic bilayered system with periodic boundary conditions are
solved using the interface-rescaling approach (IRA). The results
show that interface coupling between two sublayers would not
change the excitation energy of odd bulk modes, but change
excitation energy of even bulk modes. We call this peculiar
phenomenon the phenomenon of even bulk mode variance (PEBMV).
There are two kinds of mechanisms which cause PEBMV:
phase reversal and phase translation of the magnon at the
interface, corresponding, respectively, to the antiferromagnetic and
ferromagnetic interface coupling cases. PEBMV embodies the selective
effect of the interface on different bulk magnons. 相似文献
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Green’s function theory is applied to an alternating two-element multilayer ferromagnetic film. The Hamiltonian is based on
the Heisenberg model with a second-order uniaxial single-ion anisotropy and with the interaction between the layer in the
interfaces. Magnetization and the phase transition in such system are derived for several sets of material parameters. 相似文献
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W. P. Zhou G. H. Yun X. X. Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(1):37-42
The eigenproblems of spin waves in a heterogeneous ferromagnetic bilayer
system with periodic boundary conditions are solved using the
interface-rescaling approach. Brillouin zone mapping and the eigenmodes of
the system are investigated. We find three types of spin waves may exist in
the system: the bulk mode, the interface mode, and the perfect confined
mode. The fine structure of the energy band in the heterogeneous bilayer
system is first given for the whole two-dimensional Brillouin zone.
Conditions for the existence of the interface mode are discussed. Finally,
we analyze the resonant-confined spin waves in bulk modes and their
oscillating behavior. 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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Ze Cheng 《Physica A》2010,389(24):5671-5676
We investigate a squeezed thermal spin state of nonlinear spin waves in Heisenberg ferromagnets. In this state, the magnon system possesses a new kind of quasiparticle, the dressed magnon, whose mass is a monotonically decreasing function of temperature. The noise of one spin component in the squeezed thermal spin state can be below the noise level in the vacuum state. The magnon system undergoes a first-order phase transition from the normal state to the squeezed thermal spin state. The critical temperature is much lower than the Curie temperature. A possible detection scheme based on a polarized neutron-scattering technique is suggested. 相似文献
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Magnetostatic surface spin waves (MSSW) excited from a coplanar waveguide antenna travel in different directions with different amplitudes. This effect, called nonreciprocity of MSSW, has been investigated by micromagnetic simulations. The ratio of amplitude of two counter propagating spin waves, the nonreciprocity parameter κ, is obtained for different ferromagnetic materials, such as NiFe (Py), CoFeAl, yttrium iron garnet (YIG), and GaMnAs. A device schematic has been proposed in which κ can be tuned to a large value by varying simple geometrical parameters of the device. 相似文献