Spin Filter with Polarized Superfluid: Effects of Surface and Interface

具有偏振超流体的旋转过滤器：表面和界面的影响

• 批准号: 0138598
• 负责人: Haruo Kojima
• 金额: $ 23.18万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0138598&HistoricalAwards=false
• 关键词: Spin; Filter; Polarized; Superfluid; Effects

This research is focused on experimental investigations of the spin fluid dynamics in ferromagnetic superfluid He-3. The spin-polarized He-3 constitutes a pure, nearly ideal, material system for studying fundamental processes governing spin transport, diffusion and relaxation. Earlier experiments indicated that an "interface" between the magnetic and non-magnetic fluid He-3 could present a new channel for spin relaxation. It is proposed to provide a direct test of the importance of the interface by eliminating the interface altogether. A new spin filter experiment is proposed to create a much greater polarization than heretofore possible by inducing ferromagnetic fluid flows through a "superleak". The hydrodynamics and spin dynamics properties of such a fluid state with large non-equilibrium polarization will be studied for the first time. Experiments will be carried out with liquid He-3 cooled down to 0.5 mKelvin, in magnetic fields up to 15 Tesla. These studies of spin fluid dynamics are closely related to current research in the field of "spintronics". The proposed research has certain advantages, in that simpler macroscopic structures are involved, it is relatively easy to alter material conditions and parameters, and the relaxation or decoherence time scales are longer. The proposed work will be carried out in collaboration with the Institute for Solid State Physics of the Tokyo University. The graduate students will participate in international cooperative research. They will gain experience in the state-of-the-art technology in ultra low temperature physics and in materials physics. They will acquire a solid foundation for scientific careers in industry, academia or government laboratories. Undergraduate students will also participate in the research.This project is directed at understanding of the nature of ferromagnetic fluid dynamics. The ferromagnetic fluid state occurs when an isotope of helium, He-3, is specially cooled to ultralow temperatures. The motivation for the experiments is that novel changes in the magnetic fluid properties may occur when the fluid is made to flow through a small structure called a spin filter. The model material system is ferromagnetic liquid He-3 cooled to nearly absolute zero: about 0.0005 degrees Kelvin. In addition, a very large magnetic field, up to 15 Tesla, is required. These "extreme conditions" are only available in ultra low temperature laboratories. The work will be carried out via an international collaboration involving the Institute for Solid State Physics of the Tokyo University. The ferromagnetic He-3 is attractive because it is an ideal pure substance, free from impurities, and its magnetic relaxation properties can be related to more common or "spintronic" materials. The spin fluid dynamics provides a novel analog for spintronics device research where the spin degree of freedom of the electron is used to carry information. Hence the proposed research may ultimately contribute to spintronics device technology. The graduate students participate in international cooperative research and gain experience in the state-of-the-art technology in ultra low temperature physics and materials physics. They receive rigorous training that prepares them for careers in industry, academia or government. Undergraduate students will also participate in the research.

这项研究的重点是对铁磁超流体HE-3中自旋流体动力学的实验研究。 自旋偏振HE-3构成了一个纯粹的，几乎是理想的物质系统，用于研究控制自旋传输，扩散和放松的基本过程。 较早的实验表明，磁性和非磁性流体HE-3之间的“界面”可能会呈现出新的旋转弛豫通道。 建议通过完全消除接口来直接测试接口的重要性。 提出了一个新的自旋滤波器实验，可以通过诱导铁磁流体流过“ superleak”来产生比迄今为止可能更大的极化。 将首次研究具有较大非平衡极化的这种流体状态的流体动力学和自旋动力学特性。 实验将使用液体HE-3将其冷却至0.5 Mkelvin进行，在最高15 TESLA的磁场中。 这些旋转液动力学的研究与“旋转型”领域的当前研究密切相关。 拟议的研究具有某些优势，因为涉及更简单的宏观结构，更改材料条件和参数相对容易，并且放松或谐波时间尺度更长。 拟议的工作将与东京大学固态物理研究所合作进行。 研究生将参加国际合作研究。 他们将获得超低温度物理和材料物理学的最先进技术的经验。 他们将为工业，学术界或政府实验室的科学职业奠定坚实的基础。 本科生还将参加研究。该项目旨在了解铁磁液体动力学的性质。 当氦气He-3的同位素专门冷却至超高温度时，就会发生铁磁液状态。 实验的动机是，当使流体流过一个称为自旋滤波器的小结构时，可能会发生新的磁性流体特性变化。 模型材料系统是铁磁液体HE-3冷却至几乎绝对零：大约0.0005度开尔文。 另外，需要一个非常大的磁场，最多需要15特斯拉。 这些“极端条件”仅在超低温度实验室中可用。 这项工作将通过涉及东京大学固态物理研究所的国际合作进行。 铁磁HE-3很有吸引力，因为它是一种理想的纯物质，无杂质，其磁性松弛特性可能与更常见或更加“自旋”材料有关。 自旋流体动力学为SpinTronics设备研究提供了一种新颖的类似物，其中使用电子的自由度用于携带信息。 因此，拟议的研究最终可能有助于Spintronics Device技术。 研究生参加了国际合作研究，并在超低温度物理和材料物理学的最先进技术方面获得了经验。 他们接受了严格的培训，为行业，学术界或政府的职业做好准备。本科生还将参加这项研究。