Studies of Spin-Currents, Anomalous Hall Effect and Ballistic Electron Propagation in Quench Condensed Alkali Films

淬火凝聚碱薄膜中自旋电流、反常霍尔效应和弹道电子传播的研究

• 批准号: 0439810
• 负责人: Gerd Bergmann
• 金额: $ 32.5万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0439810&HistoricalAwards=false
• 关键词: Studies; Spin; Currents; Anomalous; Hall

This individual investigator award is to study the properties of alkali metal films that get modified when they are in contact with other materials. Alkali metals have the unique property that even in quench-condensed films the conduction electrons have long mean free paths. With quenched condensation, complex sandwiches can be prepared and the ballistic propagation of conduction electrons can be investigated in situ. Alkali films in weak contact with Fe films show strong spin currents. One focus of the proposed research is the study of spin currents and the anomalous Hall effect. Both phenomena have attracted strong interest in recent years because of their importance in the field of spintronics. Furthermore, alkali metal films have found important applications in the storage of hyperpolarized noble gases (which are used in MRI of the lungs). Only containers covered with alkali films can store the hyperpolarized noble gases over a sufficiently long time and the cause of it is not understood at present. The project introduces graduate and undergraduate students to the techniques of high vacuum, low temperature, and thin film physics. Undergraduate students who participated in previous research projects in the principal investigator's group have won first and second prizes in university-wide undergraduate research competition. Films of alkali metals became recently important in the medical application of MRI to the lungs and other air filled organs. For the MRI of the lungs, one needs hyperpolarized noble gases (for example He3). Only containers covered with alkali films can store these gases for sufficiently long times. The property of alkali metals that makes this possible is not clear at present. Within the proposed project, the modified properties of alkali films when in contact with other material will be investigated. Alkali films have the unique property that they form a rather perfect lattice even when they are condensed onto a liquid-helium-cooled substrate. Therefore, the ballistic propagation of conduction electrons can be investigated in complex multi-films of alkali and other metals. The project focuses on the investigation of spin currents in iron-alkali multi-films and the properties of thin alkali films in contact with other materials.The project introduces graduate and undergraduate students to the techniques of high vacuum, low temperature, and thin film physics and trains them as competent workers for frontier scientific research. Undergraduate students who participated in previous research projects in the principal investigator's group have won first and second prizes in university-wide undergraduate research competition.

这个个人研究者奖是研究碱金属薄膜的性质，当它们与其他材料接触时会发生变化。 碱金属具有独特的性质，即使在淬火凝聚膜中，传导电子也有长的平均自由程。 通过淬冷凝聚，可以制备复杂的三明治结构，并可以原位研究传导电子的弹道传播。 弱接触的铁膜的碱膜显示出强的自旋电流。 其中一个研究重点是自旋电流和反常霍尔效应的研究。 这两种现象近年来引起了人们的强烈兴趣，因为它们在自旋电子学领域的重要性。 此外，碱金属薄膜在超极化惰性气体（用于肺部MRI）的储存中具有重要的应用。 只有覆盖有碱性薄膜的容器才能在足够长的时间内储存超极化惰性气体，其原因目前还不清楚。 该项目向研究生和本科生介绍高真空、低温和薄膜物理技术。 曾参与主要研究者课题组前期研究项目的本科生在全校本科生科研竞赛中获得一、二等奖。碱金属薄膜最近在MRI对肺和其他充满空气的器官的医学应用中变得重要。 对于肺部的MRI，需要超极化惰性气体（例如He 3）。 只有用碱性薄膜覆盖的容器才能储存这些气体足够长的时间。使这成为可能的碱金属的性质目前尚不清楚。 在拟议的项目中，将研究碱膜与其他材料接触时的改性性能。 碱金属薄膜具有独特的性质，即使在液氦冷却的衬底上冷凝，它们也能形成相当完美的晶格。 因此，可以在复杂的碱金属和其他金属的多层膜中研究传导电子的弹道传播。 该项目主要研究铁-碱多层膜中的自旋电流以及薄碱膜与其他材料接触时的性质，向研究生和本科生介绍高真空、低温和薄膜物理技术，培养他们成为胜任前沿科学研究的人才。 曾参与主要研究者课题组前期研究项目的本科生在全校本科生科研竞赛中获得一、二等奖。