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Controll and Quantitative Analysis of Spin Disorder at Magnetic fractal Interface

磁分形界面自旋无序的控制与定量分析

基本信息

批准号：
12640330
负责人：
TAKEDA Masayasu
金额：
$ 2.37万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

It is well known that the interfacial roughness plays an important role in the giant magnetoresistance (GMR) effect of magnetic multilayers like Fe/Cr, Co/Cu and so on. The interfacial roughness, atomic disorder at the interfaces, is expected to be accompanied with the magnetic disorder. Such magnetic disorder may directly affect on the GMR effect because the spin-dependent scattering of conduction electrons at the interface is believed to be essential to the GMR effect. However, little attention has been paid to the magnetic disorder at the interface in studying the GMR effect. In addition, the meaning of the term, interfacial roughness, seems not to be well-defined. In this study we defined the interfacial rouness as that described by self-affine the Fractal interface and made an effort to establish the quantitative analysis of the magnetic interfacial roughness.A focusing polarizing neutron device which consists of Fe/Si supermirrors was installed at a polarized neutron reflectometer, PORE, at High Energy Accelerator Organization in order to increase the intensity of incident polarized neutrons. We have successfully increased the neutrons more than twice using the new device.The correlation between interfacial roughness and the GMR effect in epitaxial Fe/Cr(001) multilayers was investigated by neutron and X-ray reflectivity measurements. The specimens were annealed under various conditions in vacuum so as to have different interfacial roughnesses. The detailed profile of the off-specula reflection was quantitatively analyzed by the self-affine-Fractal interface model. The magnetic interfacial roughness were very sensitive to the annealing process, on the other hand, those for the atomic interfacial roughness were less sensitive. This suggests that the magnetic interfacial foughness in dominant over the atomic interfacial roughness for the spin-independent electron scattering at the interface which is a disadvantage to the GMR effect.

众所周知，界面粗糙度对Fe/Cr、Co/Cu等磁性多层膜的巨磁阻（GMR）效应起着重要作用。界面粗糙度、界面处的原子无序预计会伴随着磁无序。这种磁紊乱可能直接影响 GMR 效应，因为界面处传导电子的自旋相关散射被认为对 GMR 效应至关重要。然而，在研究GMR效应时，很少关注界面处的磁紊乱。此外，界面粗糙度这个术语的含义似乎也没有明确的定义。在这项研究中，我们将界面粗糙度定义为自仿射分形界面描述的界面粗糙度，并致力于建立磁界面粗糙度的定量分析。在高能加速器组织的偏振中子反射计PORE上安装了由Fe/Si超级镜组成的聚焦偏振中子装置，以增加入射偏振中子的强度。我们使用新装置成功地将中子增加了两倍以上。通过中子和X射线反射率测量研究了外延Fe/Cr(001)多层膜中界面粗糙度与GMR效应之间的相关性。样品在真空中的不同条件下退火以获得不同的界面粗糙度。通过自仿射分形界面模型定量分析了非镜面反射的详细轮廓。磁性界面粗糙度对退火过程非常敏感，而原子界面粗糙度则不太敏感。这表明，对于界面处自旋无关的电子散射，磁性界面粗糙度优于原子界面粗糙度，这对 GMR 效应是不利的。