Proximity-Coupled Normal Metals and Ferromagnets

该个人研究者奖支持一个项目，该项目将研究由超导(S)、普通金属(N)和铁磁(F)元素制成的金属异质结构的电学和磁性。目的是探索FS结构中铁磁性和超导性相互作用的本质，并研究长程相相干对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验证与超导体接触的扩散铁磁体中存在远程超导相关。此外，还将研究铁磁体中有限自旋极化对FS结构输运性质的影响。利用一种新颖的局部测温技术，将探讨NS器件的热功率以及NS结构的热导率的影响。样品将通过电子束光刻制作，并使用各种低温恒温器（包括稀释冰箱和3He冰箱）在毫开尔文温度下进行测量。在这个项目中训练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充分准备。超导体是在低温下表现出许多不寻常的电和磁特性的材料，最著名的特性是它们能够无电阻地携带电流。这些特性构成了许多有用应用的基础，例如非常高的磁场磁铁。当超导体与传统的普通金属（如铜或金）或铁磁铁（如铁或镍）接触良好时，两种不同元素之间的相互作用会产生具有潜在设备应用价值的新效应。该项目的目标是研究放置在超导体附近的普通金属和铁磁体的电和热输运性质。结合铁磁体和超导体结构的电学性质将被研究，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普通金属中的热传递。这些测量将帮助我们进一步了解超导体、铁磁体和普通金属在非常小尺寸尺度上的相互作用。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。在这个项目中接受培训的博士后助理和研究生将接触到许多实验技术，这些技术将对未来在工业界或学术界的职业生涯有用。

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.