Perpendicular-Current Spin-Polarized Transport Studies

该计划涉及两个在计算机行业具有潜在应用价值的相关项目。密歇根州立大学(MSU)的一组研究人员将调查和操纵交替的铁磁性和非磁性金属层的磁性。在第一个项目中，将对精心挑选的金属对之间的界面的比电阻进行精确测量，其量等于样品面积及其电阻的乘积。将这些结果与计算结果进行比较，将检验我们目前对磁性多层膜中电子输运的理解，从而为未来的工艺设计提供基础。第二个项目涉及金属磁性多层膜中的电流感应磁化转换。这项研究对于写入磁性随机存取存储器以及作为潜在的新一代读取头中不想要的噪声的可能来源都是非常有意义的。为了验证预测，密歇根州立大学的研究小组将测量开关电流和磁阻如何随着许多不同的磁性和非磁性金属层的组合而变化，这些金属层是使用他们多功能的纳米制造设备制备的。通过参与这个项目，研究生和本科生将获得规划和开展前沿科学研究的经验。该项目还包括与法国和荷兰的科学家合作。直到最近，人们还认为，在计算机中存储信息所需的磁性层中的磁化反转可以通过施加外部磁场来实现。密歇根州立大学的一组研究人员帮助证明，在垂直于多层膜的方向传递足够大的电流可以诱导磁化转换。为了实现这一点，多层膜的横向尺寸需要小于1微米，这需要现代的“纳米制造”技术。这项拟议的研究将研究磁性和非磁性金属多层膜的不同组合，以了解电流感应磁化转换背后的物理基础。研究小组将对精心挑选的金属对之间的界面进行精确的电磁性能测量。这些测量与计算的比较将检验我们对磁性多层膜中电子输运的基本理解，从而为工艺设计提供依据。这些项目可能会带来用于计算机硬盘的新设备。通过参与这个项目，研究生和本科生将获得规划和开展与技术进步直接相关的前沿科学研究的经验。该项目还包括与其他国家的科学家合作。

This program involves two related projects with potential applications in the computer industry. A team of researchers at the Michigan State University (MSU) will investigate and manipulate the magnetic properties of alternating ferromagnetic and nonmagnetic metal layers. In the first project, precision measurements of the specific resistance, a quantity equal to the product of the sample area and its electrical resistance, of interfaces between carefully chosen pairs of metals will be made. Comparison of these results with calculations will test our current understanding of the electronic transport in magnetic multilayers, thereby providing the basis for future technological designs. The second project deals with current-induced magnetization switching in metallic magnetic multilayers. This study is of great interest both for writing magnetic random access memory and as a possible source of unwanted noise in potential new generation read-heads. To test predictions, the MSU group will measure how both the switching current and the magnetoresistance vary with many different combinations of magnetic and non-magnetic metal layers, prepared using their versatile nano-fabrication facilities. By participating in this project, graduate and undergraduate students will gain experience in planning and carrying out cutting-edge scientific research. The program also involves collaborations with scientists in France and Holland. Until recently, it was assumed that reversal of magnetization in magnetic layers, needed for information storage in computers, could be effected by applying an external magnetic field. A team of researchers at the Michigan State University has helped to show that passing a large enough current in the direction perpendicular to the multilayer can induce magnetization switching. In order to achieve this, the lateral dimensions of the multilayer need to be less than one micrometer, which requires modern "nanofabrication" techniques. The proposed research will study different combinations of magnetic and non-magnetic metal multilayers to understand the physics underlying current-induced magnetization switching. The research team will make precision measurements of the electrical and magnetic properties of the interfaces between carefully chosen pairs of metals. Comparison of these measurements with calculations will test our fundamental understanding of electronic transport in magnetic multilayers, thereby providing the basis for technological design. These projects could lead to new devices for use in computer hard disks. By participating in this project, graduate and undergraduate students will gain experience in planning and carrying out cutting-edge scientific research that directly relates to technological progress. The program also involves collaborations with scientists in other countries.