Perpendicular-Current Spin-Polarized Transport Studies

该计划涉及两个相关的项目，在计算机行业有潜在的应用。密歇根州立大学（MSU）的一组研究人员将研究和操纵铁磁性和非磁性交替金属层的磁性。在第一个项目中，将对精心选择的金属对之间的界面进行特定电阻的精确测量，该电阻等于样品面积与其电阻的乘积。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中的电子输运的理解，从而为未来的技术设计提供基础。第二个项目涉及金属磁性多层中的电流感应磁化开关。本研究对于写入磁性随机存取存储器和作为潜在的新一代读头中不需要的噪声的可能来源具有很大的兴趣。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电阻如何随磁性和非磁性金属层的许多不同组合而变化，这些金属层是用他们的多功能纳米制造设备制备的。通过参与该项目，研究生和本科生将获得规划和开展前沿科学研究的经验。该项目还涉及与法国和荷兰科学家的合作。直到最近，人们还认为，计算机信息存储所需的磁性层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已经帮助证明，在垂直于多层的方向上通过足够大的电流可以诱导磁化开关。为了实现这一点，多层的横向尺寸需要小于1微米，这需要现代的“纳米制造”技术。该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开关的物理原理。研究小组将对精心挑选的金属对之间的界面的电和磁特性进行精确测量。将这些测量结果与计算结果进行比较，将检验我们对磁性多层中的电子输运的基本理解，从而为技术设计提供基础。这些项目可能会产生用于计算机硬盘的新设备。通过参与本项目，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。该项目还涉及与其他国家科学家的合作。

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.