Proximity-Coupled Normal Metals and Ferromagnets

邻近耦合普通金属和铁磁体

• 批准号: 0201530
• 负责人: Venkat Chandrasekhar
• 金额: $ 30万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-01 至 2005-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0201530&HistoricalAwards=false
• 关键词: Proximity; Coupled; Normal; Metals; Ferromagnets

This individual investigator award supports a project that will investigate the electrical and magnetic properties of metallic heterostructures fabricated from superconducting (S), normal metal (N), and ferromagnetic (F) elements. The goal is to explore the nature of the interaction between ferromagnetism and superconductivity in FS structures, and to investigate the influence of long-range phase coherence on the thermal transport in NS heterostructures. Electrical transport properties of FS heterostructures, will be used to attempt to verify the existence of long-range superconducting correlations in a diffusive ferromagnet placed in contact with a superconductor. In addition, effects of finite spin polarization in the ferromagnet on the transport properties of FS structures will be studied. Using a novel local thermometry technique, effects in the thermopower of NS devices, as well the thermal conductance of NS structures, will be explored. Samples will be fabricated by electron-beam lithography and measured at millikelvin temperatures using various low temperature cryostats, including a dilution refrigerator and a 3He refrigerator. The students and post-docs trained on this project will gain experience with both microfabrication and low temperature techniques. Thus becoming well-prepared for careers in industry, academia or government laboratories. Superconductors are materials that show a number of unusual electrical and magnetic properties at low temperatures, the best known property being their ability to carry an electrical current without resistance. These properties form the basis for a number of useful applications, such as very high field magnets. When a superconductor is placed in good contact with a conventional normal metal such as copper or gold, or a ferromagnet like iron or nickel, the interaction between the two different elements results in new effects with potential device applications. The goal of this project is to investigate the electrical and thermal transport properties of normal metals and ferromagnets placed in close proximity to a superconductor. Electrical properties of structures incorporating ferromagnets and superconductors will be studied to investigate the interplay between magnetism and superconductivity in very small devices. In addition, heat transport in a normal metal placed in contact with a superconductor will be explored. These measurements will help us gain further insight into the interaction between superconductors, ferromagnets and normal metals on very small size scales. The samples for these experiments will be fabricated using advanced electron-beam lithography techniques, and measured using sophisticated techniques at temperatures near absolute zero. Post-doctoral associates and graduate students trained on this project will be exposed to a number of experimental techniques which will be useful in future careers in either industry or academia.

这个个人研究者奖支持一个项目，该项目将研究由超导（S），正常金属（N）和铁磁（F）元素制造的金属异质结构的电和磁特性。 目的是探索FS结构中铁磁性和超导性之间相互作用的本质，并研究长程相位相干性对NS异质结构中热输运的影响。 FS异质结构的电输运性质，将被用来试图验证在与超导体接触放置的扩散铁磁体的长程超导关联的存在。 此外，有限自旋极化的铁磁体上的FS结构的输运性质的影响将被研究。 使用一种新的局部测温技术，在NS设备的热功率的影响，以及NS结构的热导率，将进行探讨。 样品将通过电子束光刻制造，并使用各种低温低温恒温器（包括稀释冰箱和3He冰箱）在毫开尔文温度下进行测量。 在这个项目上接受培训的学生和博士后将获得微加工和低温技术的经验。 从而为工业，学术界或政府实验室的职业生涯做好准备。 超导体是一种在低温下表现出许多不寻常的电和磁特性的材料，最为人所知的特性是它们能够在没有电阻的情况下携带电流。 这些性质形成了许多有用应用的基础，例如非常高的磁场磁体。 当超导体与传统的正常金属（如铜或金）或铁磁体（如铁或镍）良好接触时，两种不同元素之间的相互作用会产生新的效应，并具有潜在的器件应用。 这个项目的目标是研究放置在超导体附近的正常金属和铁磁体的电和热输运性质。 将研究铁磁体和超导体结合的结构的电学性质，以研究在非常小的器件中磁性和超导性之间的相互作用。 此外，将探讨与超导体接触的正常金属中的热传输。 这些测量将帮助我们进一步了解超导体，铁磁体和正常金属之间的相互作用在非常小的尺寸尺度。 这些实验的样品将使用先进的电子束光刻技术制造，并在接近绝对零度的温度下使用复杂的技术进行测量。 在这个项目上培训的博士后助理和研究生将接触到一些实验技术，这些技术将在工业或学术界的未来职业生涯中有用。