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.

该单独的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）和铁磁元素（F）元素制造的金属异质结构的电和磁性特性。 目的是探索FS结构中铁磁和超导性之间相互作用的性质，并研究远程相一致性对NS异质结构中热传输的影响。 FS异质结构的电运输特性将用于试图验证与超导体接触的扩散铁磁铁中远程超导相关的存在。 此外，将研究铁磁体中有限自旋极化对FS结构传输特性的影响。 使用一种新型的局部温度计技术，将探索NS设备的热电器的效果以及NS结构的热电导。 样品将通过电子束光刻制造，并在Millikelvin温度下使用各种低温低温器（包括稀释冰箱和3HE冰箱）进行测量。 接受该项目培训的学生和培训后将获得微加工和低温技术的经验。 因此，为工业，学术界或政府实验室的职业准备好了。 超导体是在低温下显示出许多异常电气和磁性特性的材料，最著名的特性是它们携带无电流的电流的能力。 这些属性构成了许多有用的应用，例如非常高的场磁铁。 当将超导体与传统的正常金属（例如铜或金）或铁或镍等铁磁体（例如铁或镍）保持良好接触时，两个不同元素之间的相互作用会与潜在的设备应用产生新的效果。 该项目的目的是研究正常金属和铁磁体的电气和热传输特性，与超导体紧密相近。 将研究结合铁磁体和超导体的结构的电性能，以研究非常小的设备中磁性和超导性之间的相互作用。 此外，将探索与超导体接触的普通金属中的热传输。 这些测量结果将有助于我们进一步深入了解非常尺寸的超导体，铁磁体和正常金属之间的相互作用。 这些实验的样品将使用高级电子束光刻技术制造，并在绝对零的温度下使用复杂的技术进行测量。 接受该项目的培训的博士后伙伴和研究生将接触到许多实验技术，这些技术将在行业或学术界的未来职业中有用。