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高自旋极化氧化物材料的颗粒边界磁电阻效应 总被引:2,自引:0,他引:2
颗粒边界磁电阻是高自旋极化氧化物颗粒体系中由于颗粒边界的存在而导致显著的磁电阻效应。本文将这种磁电阻效应定义为颗粒边界磁电阻效应。这里所说的颗粒边界,包括各种自然和人工晶界、粉末颗粒表面、复合材料中的颗粒界面等多种情况;所涉及的材料包括高自旋极化氧化物多晶、压缩粉末和各种复合材料等。对颗粒边界磁电阻效应的研究,不仅有助于人们进一步理解高自旋极化氧化物磁输运性质的基本机制,并为寻求具有高磁电阻效应的新型自旋电子学器件提供理论基础。本文综述了高自旋极化氧化物颗粒边界磁电阻研究的主要背景和发展现状,介绍了该领域中主要的实验发现和理论模型,展望了未来的发展。 相似文献
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颗粒边界磁电阻是高自旋极化氧化物颗粒体系中由于颗粒边界的存在而导致显著的磁电阻效应。本文将这种磁电阻效应定义为颗粒边界磁电阻效应。这里所说的颗粒边界,包括各种自然和人工晶界、粉末颗粒表面、复合材料中的颗粒界面等多种情况;所涉及的材料包括高自旋极化氧化物多晶、压缩粉末和各种复合材料等。对颗粒边界磁电阻效应的研究,不仅有助于人们进一步理解高自旋极化氧化物磁输运性质的基本机制,并为寻求具有高磁电阻效应的新型自旋电子学器件提供理论基础。本文综述了高自旋极化氧化物颗粒边界磁电阻研究的主要背景和发展现状,介绍了该领域中主要的实验发现和理论模型,展望了未来的发展。 相似文献
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文章介绍了2004年度国家自然科学二等奖获奖成果[21].类钙钛矿型材料是一类物理内涵极其丰富的化合物,它是著名的高温超导材料、铁电材料、压电材料,又是庞磁电阻效应材料,目前又显示出具有大磁熵变效应与隧道磁电阻效应.文章作者系统地研究了锰钙钛矿磁性化合物的磁熵变与组成、微结构以及颗粒尺寸的关系,研究结果表明,磁性钙钛矿化合物具有显著的磁熵变,居里温度易调,并且化学稳定性佳,从而成为一类新型的磁制冷工质候选材料.此外,文章作者还研究了钙钛矿化合物纳米颗粒体系的磁电阻效应,发现除人们发现的居里温度附近的本征的庞磁电阻效应外,在很宽的低温区,存在与温度不甚敏感的隧道磁电阻效应. 相似文献
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磁电子学中的若干问题 总被引:32,自引:0,他引:32
本文综述了自旋极化输运过程中巡游电子的自旋极化、自旋相关的散射及自旋弛豫等三方面的内容;全面总结了铁磁金属的磁电阻效应(AMR)、磁性金属多层膜和颗粒膜的巨磁电阻效应(GMR)、氧化物铁磁体的特大磁电阻效应(CMR)以及磁隧道结的巨大隧道电阻效应(TMR)研究中具有代表性的实验结果及理论模型;简单介绍了新生的磁电子器件—磁电阻型随机存取存储器(MRAM)和全金属自旋晶体管的工作原理和工作过程。 相似文献
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研究磁性半导体中负磁电阻产生机理对正确理解载流子与磁性离子间的sp.d磁交换作用是非常重要的.通过变温(10-300K)磁输运和变温(5-300K)磁化率实验研究了一系列不同Mn含量非简并P型Hgl-xMn。Te单晶佃〉0.17)的负磁电阻和顺磁增强效应.实验结果表明其负磁电阻与温度的关系和磁化率与温度的关系基本一致,两者都包含一个呈指数型变化的温度函数exp(-K/T).根据磁性半导体的杂质能级理论,非简并P型H譬1-xMnxTe单晶在低磁场范围内出现负磁电阻效应的主要物理机理为外磁场的磁化效应使得受主杂质或受主型束缚磁极化子的有效电离能减小. 相似文献
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简要回顾了利用量子隧道效应测定铁磁金属传导电子自旋极化率的研究历史,综述了自旋极化电子隧穿产应导致的“铁磁金属/非磁绝缘体/铁磁金属”三层平面型隧道结中的巨磁电阻效应以及“铁磁金属/非磁绝缘体”颗粒膜系统中的隧穿类型巨磁电阻效应的研究进展。 相似文献
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在线非接触测试巨磁电阻效应对磁电子器件的工业化生产具有重要的意义 .用红外光谱研究了 (CoFe) 1 -xAgx颗粒薄膜的磁折射效应 ,研究表明在红外波段 ,一级近似可以认为巨磁电阻比值与磁折射变化率成正比 ,可以利用磁折射效应作为在线非接触工具测量与自旋散射相关的巨磁电阻效应 . 相似文献
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First we calculate the Wigner phase-space distribution function for the Klein-Gordan Landau problem on a commmutative space. Then we study the modifications introduced by the coordinate-coordinate noncommuting and momentum-momentum noncommuting, namely, by using a generalized Bopp's shift method we construct the Wigner function for the Klein-Gordan Landau problem both on a noncommutative space (NCS) and a noncommutative phase space (NCPS). 相似文献
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K. Harada H. Kuratsuji 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(2):193-198
We study a dynamics of texture for a two-component spinor bose condensate.
This is carried out by adopting a time dependent Landau-Ginzburg Lagrangian for
a spinor order parameter. By using a polar form of the spinor order parameter, we obtain
a field equation for the texture. In particular we consider a one dimensional model in which we can obtain analytic forms
for the textures in terms of elliptic functions of several kinds.
We find that these solutions are characterized by a modulus parameter, and changes in this parameter cause structural changes
of texture. 相似文献
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《Journal of Geometry and Physics》2006,56(8):1370-1386
In this paper, after some recalls about Poisson cohomology, we first study what the general method is in order to obtain a bi-Hamiltonian formulation of a given Hamiltonian system by means of a deformation. Then we show that the bi-Hamiltonian formulation which results from the deformation of a Poisson structure by means of a suitable non-Noether symmetry cannot explain the complete integrability for a large class of Arnold–Liouville integrable systems; next we prove that the deformation must be made in this context by a suitable mastersymmetry. At last, we give several examples. 相似文献
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In this paper, we investigate an eigenvalue problem for a biharmonic operator on a bounded domain in an n-dimensional Euclidean space, which is also called a buckling problem. We introduce a new method to construct ``nice' trial
functions and we derive a universal inequality for higher eigenvalues of the buckling problem by making use of the trial functions.
Thus, we give an affirmative answer for the problem on universal bounds for eigenvalues of the buckling problem, which was
proposed by Payne, Pólya and Weinberger in [14] and this problem has been mentioned again by Ashbaugh in [1].
Research partially supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.
Research partially supported by SF of CAS 相似文献
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Tian Feng Zhihua Guo Huaixin Cao 《International Journal of Theoretical Physics》2016,55(12):5202-5215
Maximally entangled states, defined as those states that have the maximal entanglement of formation under some entanglement measure, are the ideal resource for many quantum missions. In this paper, we call a convex roof of maximally entangled pure states a quasi maximally entangled state. First, we present the concept of a witness for non-quasi maximally entangled states, which is an observable that can distinguish some non-quasi maximally entangled states from quasi maximally entangled ones. Then we prove that every non-quasi maximally entangled state can be witnessed by a witness and obtain some necessary and sufficient conditions for an observable to be a witness for non-quasi maximally entangled states. Lastly, we give some classes of Hermitian operators, which can become witnesses. Especially, we compute non-quasi maximally entangled states that can be detected by a specific product operator. 相似文献
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Truly by looking through the analytical model of constituent quarks and further theimportance of the effects of relativity on quark dynamics in studying the interior structure of mesons,in this research we have strived to have a much more precise modeling for quark interior structure.Certainly by observing the constituent model of quarks, at first we consider the mesons as two-body system,then we place the considered calculated Potential, which is a function of location and spin,in Schrödinger's equation. Next we will solve the mentioned equation in analytical method. Moving on this solution,we will import the spin and isospin interactions as perturbation in our problem,and finally by using these solutions we can obtain both binding energy and wave function for bound state and excited states of meson.Eventually, by applying these calculations in the next and last step we will compare our data about meson'sbinding energy and masses with others results. 相似文献
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An Iterative Two-Grid Method of a Finite Element PML Approximation for the Two Dimensional Maxwell Problem 下载免费PDF全文
Chunmei Liu Shi Shu Yunqing Huang Liuqiang Zhong & Junxian Wang 《advances in applied mathematics and mechanics.》2012,4(2):175-189
In this paper, we propose an iterative two-grid method for the edge finite
element discretizations (a saddle-point system) of Perfectly Matched Layer (PML)
equations to the Maxwell scattering problem in two dimensions. Firstly, we use
a fine space to solve a discrete saddle-point system of $H(grad)$ variational problems,
denoted by auxiliary system 1. Secondly, we use a coarse space to solve the
original saddle-point system. Then, we use a fine space again to solve a discrete$\boldsymbol{H}(curl)$-elliptic variational problems, denoted by auxiliary system 2. Furthermore,
we develop a regularization diagonal block preconditioner for auxiliary system 1
and use $H$-$X$ preconditioner for auxiliary system 2. Hence we essentially transform
the original problem in a fine space to a corresponding (but much smaller)
problem on a coarse space, due to the fact that the above two preconditioners are
efficient and stable. Compared with some existing iterative methods for solving
saddle-point systems, such as PMinres, numerical experiments show the competitive
performance of our iterative two-grid method. 相似文献
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We derive a number of local identities involving Jacobi elliptic functions and use them to obtain several new results. First,
we present an alternative, simpler derivation of the cyclic identities discovered by us recently, along with an extension
to several new cyclic identities. Second, we obtain a generalization to cyclic identities in which successive terms have a
multiplicative phase factor exp(2iπ/s), wheres is any integer. Third, we systematize the local identities by deriving four local ‘master identities’ analogous to the master
identities for the cyclic sums discussed by us previously. Fourth, we point out that many of the local identities can be thought
of as exact discretizations of standard non-linear differential equations satisfied by the Jacobi elliptic functions. Finally,
we obtain explicit answers for a number of definite integrals and simpler forms for several indefinite integrals involving
Jacobi elliptic functions. 相似文献