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THEORETICAL STUDY IN NANO-PHYSICS OF MAGNETIC ATOM BRIDGES CONTROLLED BY THE STM TIP MANIPULATIONS - NANO-STRUCTURE, NANO-MAGNETISM

STM 尖端操控控制磁原子桥的纳米物理理论研究 - 纳米结构、纳米磁性

基本信息

批准号：
13650026
负责人：
NAKANISHI Hiroshi
金额：
$ 2.24万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

We investigated the nano-physics : nano-lattice-structure, nano-magnetism, and quantum transport, of the magnetic atom bridges constructed between a tip of a scanning tunneling microscope (STM) and a solid surface with the aid of first-principles calculation based on the density functional theory.We show the origin of a change in the magnetic state induced by the STM-tip manipulation and how the change in the magnetic state affects the electron transport phenomena by use of the Fe atom bridge of the simple structure, the linear chain structure. As a result of total energy calculation, the Fe atom bridge of the linear chain structure is unstable and its lattice is too weak to show the change in the magnetic state. The stable atom bridge is of the zigzag chain structure, whose magnetic state is always high-spin ferromagnetic stateWe searched the stable structure of the atom bridge whose lattice structure is enough strong to show a change in the magnetic state. We have found such a stable … More structure. That is the twisted ladder structure. The Fe atom bridge with a twisted ladder structure is stable enough to undergo changes in its magnetic state via compression in length. We showed that it is possible to control the magnetic state by the STM-tip manipulations.We have also investigated the magnetic properties of magnetic alloy atom bridges. In the case of an Fe_<1-x>Ni_x alloy atom bridge, we have found that the atoms maintain a considerably large magnetic moment (about 3μB for an Fe atom and about 0.9μB for a Ni atom), and that the mean magnetic moment per atom in the atom bridge decreases linearly as x increases. In the case of an Fe_xV_<1-x> alloy atom bridges shows a strong contrast with that of the Fe_<1-x>Ni_x alloy atom bridges, and similarities with the bulk of the corresponding alloy, except for the case of x=1.0. In the Fe_<1-x>V_x alloy atom bridge, a V atom has no magnetic moment, and an Fe atom has a smaller magnetic moment than that in the bulk Fe crystal. The magnetic moment of the Fe atom in the Fe-V alloy atom bridge is strongly reduced by the Fe-V atom mixing. These results give us the atom bridge version of the Pauling-Slater curve.Furthermore, we have determined the spin transport phenomena trough these atom bridges. We think that such a systematic investigation gives us the important and useful information in order to establish a basis for the design and fabrication of the atom bridge related nano-spin-electronics devices. Less

我们研究了纳米物理学：纳米晶格结构、纳米磁性和量子输运，利用基于密度泛函理论的第一性原理计算方法，研究了扫描隧道显微镜（STM）针尖与固体表面之间的磁性原子桥，揭示了STM针尖与固体表面之间磁性原子桥的形成机制，揭示了STM针尖与固体表面之间磁性原子桥的形成机制。利用Fe原子桥的简单结构，线性链结构，尖端操纵和磁状态的变化如何影响电子输运现象。总能量计算的结果表明，线性链状结构的Fe原子桥是不稳定的，其晶格太弱，不能显示磁性状态的变化。稳定的原子桥为锯齿形链状结构，其磁态始终为高自旋铁磁态。我们寻找了晶格结构足够强的原子桥的稳定结构，以显示磁态的变化。我们找到了这样一个稳定的 ...更多信息结构这就是扭曲的阶梯结构。具有扭曲梯形结构的Fe原子桥足够稳定，可以通过长度压缩来改变其磁性状态。我们证明了用STM针尖操纵来控制磁性状态是可能的，并研究了磁性合金原子桥的磁性。对于Fe_<1-x>Ni_x合金原子桥，我们发现原子保持着相当大的磁矩（Fe原子约为3μB，Ni原子约为0.9μB），原子桥中每个原子的平均磁矩随x的增加而线性减小。Fe_xV_x<1-x>合金的原子桥与Fe_<1-x>Ni_x合金的原子桥形成强烈的对比，而与相应合金体相的原子桥相似（x=1.0的情况除外）。在Fe_<1-x>V_x合金原子桥中，V原子没有磁矩，Fe原子的磁矩小于体相Fe原子的磁矩。Fe-V合金原子桥中Fe原子的磁矩被Fe-V原子混合强烈地降低。这些结果给出了原子桥形式的Pauling-Slater曲线，并进一步确定了通过这些原子桥的自旋输运现象。我们认为，这样一个系统的研究为我们提供了重要的和有用的信息，为原子桥相关的纳米自旋电子器件的设计和制造奠定了基础。少