Tunneling Studies of Ferromagnetic Junctions and Interfaces

小行星9730908 这个实验研究项目是关于电子隧道结与电极的磁性金属设想在这样一种方式，隧道电流控制在一个敏感的 时尚 通过 施加的 磁 领域 将在清洁和超高真空条件下制备表征良好的铁磁隧道结和界面，以实现精确和可重复的隧道测量，特别是在具有3d和4f铁磁金属的结构上。构成隧道结的相同薄膜的自旋极化也将通过超导隧道光谱测量。 主要的推力是了解的物理机制负责观察到的磁场灵敏度。预计这项研究将导致凝聚态物理学的新成果和新技术以及磁技术的新应用。这项研究计划是跨学科的性质，通常涉及几名本科生和高中生的活动。这些参与有利于学生为进一步学习和在工业，政府实验室或学术界的职业生涯做好准备。 %这个实验研究项目是关于一类新的 PI在其先前支持的工作中发现的电子设备，对磁场高度敏感。当器件置于磁场中时，器件的电阻（称为隧道结）会发生变化，并且据说会表现出磁阻。这一发现引起了全世界的兴趣，因为技术有改进的潜力。主要的技术应用可以是用于计算机硬盘驱动器的磁传感器，可能用于磁性计算机存储器或逻辑元件，以及用于诸如测量旋转速度的传感器的杂项应用，例如转速计。基本的隧道结是一种类似电容的器件，在两个金属板之间有一层薄的绝缘氧化物。在这种情况下，氧化物层是如此之薄，以至于电子可以通过量子力学隧穿过程从一个板转移到另一个板。 在20世纪60年代后期，基础物理研究人员已经牢固地建立并详细了解了该过程，他们意识到，如果可以用足够薄且均匀的氧化物层来制造隧道结器件，则可以有助于 理解超导性的本质 Ivar Giaever因其基于超导性的实验而获得1973年诺贝尔物理学奖。 对 他改进了制造技术， 更全面地了解 隧道结 目前的PI已经从这些早期的基础研究结果中找到了在计算机和其他技术中应用非常有前途的磁效应。 正如在前面的情况下，PI在这里已经完善了新的和更仔细的实验方法，以清楚地揭示理论上预期的物理效应，在这种情况下，磁性的性质。 这个项目的重点是仔细和系统的测量 连接 结构 与金属 电极 的 不同的铁磁成分，以便更好地理解和最大限度地提高对磁场的敏感性。该研究计划是跨学科的性质，通常涉及几个本科生和高中学生在其活动。 这些参与有利于学生为进一步的学习做好准备。 研究 和 的职业生涯 工业， 政府实验室或学术界。 ***

9730908 Moodera This experimental research project is concerned with electron tunnel junctions with electrodes of magnetic metals conceived in such a way that the tunneling current is controlled in a sensitive fashion by an applied magnetic field. Well characterized ferromagnetic tunnel junctions and interfaces will be prepared under clean and ultra high vacuum conditions to allow accurate and reproducible tunneling measurements, particularly on structures with 3d and 4f ferromagnetic metals. Spin polarization of the same films that make up the tunnel junction will also be measured by superconducting tunneling spectroscopy. The main thrust is to understand the physical mechanisms responsible for the observed magnetic field sensitivity. It is expected that this research will additionally lead to new results and techniques in condensed matter physics and new applications for magnetic technology.This research program is interdisciplinary in nature and has typically involved several undergraduate and high school students in its activities. These involvements are beneficial in the preparation of students for further study and for careers in industry, government laboratories or academia. %%% This experimental research project is concerned with a new class of electronic devices that the PI has discovered in his previously supported work, which are highly sensitive to magnetic field. The electrical resistance of the device, which is called a tunnel junction, changes when the device is placed in a magnetic field, and is said to exhibit magnetoresistance. This discovery has created interest worldwide because of the potential for improvements in technology. The main technological applications may be in magnetic sensors for computer hard drives, possibly for magnetic computer memory or logic elements, and for miscellaneous applications s uch as sensors to measure rotational speeds, eg, a tachometer. The basic tunnel junction is a capacitor-like device with a thin insulating oxide between two metal plates. In this case the oxide layer is so thin that electrons can transfer from one plate to the other by the quantum mechanical tunneling process. This process was firmly established and understood in detail in the late 1960's by basic physics researchers who realized that a tunnel junction device, if it could be fabricated with a sufficiently thin and homogeneous oxide layer, could be instrumental to understanding the nature of superconductivity. Ivar Giaever won the Nobel Prize in Physics in 1973 for his experiments on superconductivity which were based on his development of improved fabrication techniques and a more complete understanding of the physical behavior of tunnel junctions. The present PI has gone on from these earlier basic research results to find the magnetic effects which are very promising for applications in computers and other technologies. As in the earlier case, the PI here has perfected new and more careful experimental methods to clearly reveal the theoretically expected physical effects, in this case magnetic in nature. This project focuses on careful and systematic measurements on junction structures with metal electrodes of different ferromagnetic compositions, in order to better understand and maximize the sensitivity to magnetic field. This research program is interdisciplinary in nature and has typically involved several undergraduate and high school students in its activities. These involvements are beneficial in the preparation of students for further study and for careers in industry, government laboratories or academia. ***