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

这个个人研究者奖是为了研究碱金属薄膜的性质，当它们与其他材料接触时，它们会被修饰。碱金属具有独特的性质，即使在淬缩薄膜中，传导电子也有很长的平均自由程。通过淬火冷凝，可以制备复杂的夹层，并可以原位研究导电电子的弹道传播。碱膜与铁膜弱接触时表现出较强的自旋电流。提出的研究重点之一是自旋电流和反常霍尔效应的研究。由于这两种现象在自旋电子学领域的重要性，近年来引起了人们的强烈兴趣。此外，碱金属薄膜在储存超极化惰性气体（用于肺部MRI）方面也有重要的应用。只有覆盖有碱膜的容器才能将超极化惰性气体储存足够长的时间，其原因目前尚不清楚。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。曾参与主研组科研项目的本科生曾在全校本科生科研竞赛中获得一、二等奖。近年来，碱金属薄膜在肺部和其他充满空气的器官的核磁共振医学应用中变得很重要。对于肺部的核磁共振，需要超极化惰性气体（例如He3）。只有覆盖有碱膜的容器才能将这些气体储存足够长的时间。使这成为可能的碱金属的性质目前尚不清楚。在拟建项目中，将研究碱膜与其他材料接触时的改性性能。碱膜有一种独特的性质，即使在液氦冷却的衬底上凝结，它们也能形成相当完美的晶格。因此，可以研究导电电子在碱和其他金属复合薄膜中的弹道传播。本项目主要研究铁碱复合膜中的自旋电流以及与其他材料接触的碱薄膜的性能。本项目向研究生和本科生介绍高真空、低温和薄膜物理技术，培养他们成为从事前沿科学研究的合格工作者。曾参与主研组科研项目的本科生曾在全校本科生科研竞赛中获得一、二等奖。

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.