Order Parameter Structure in Thin Films and Disordered Superfluid 3He

薄膜和无序超流体 3He 中的有序参数结构

• 批准号: 0244099
• 负责人: William Halperin
• 金额: $ 60.8万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0244099&HistoricalAwards=false
• 关键词: Order; Parameter; Structure; Thin; Films

This project will investigate the influence of disorder on superfluid 3He, one of an important class of quantum fluids that includes ruthenate superconductors, heavy fermion superconductors, and high temperature superconductors. These unconventional systems are formed from pairs of fermions in BCS states. They all have the common important characteristic of spontaneously broken symmetries beyond gauge symmetry. As such they are particularly sensitive to impurity effects, which must be investigated if the underlying behavior of these systems is to be understood and if the potential for their application is to be realized. The proposed research will bring precise experimental tools, transverse high frequency acoustics, heat capacity, and thin film methods, that are available for 3He in aerogel glass, to determine order parameter suppression and the density of low-lying excitations and to compare with recent theoretical predictions for gapless superconductivity. The results will have broad implications for unconventional superconductors, Bose-Einstein condensation, and exotic vortex matter. The participation of graduate students in this work will provide them with technical training relevant to basic research and industrial interests. Undergraduate projects on acoustics will give opportunities for learning complementary to, but outside, the classroom. This project will investigate the influence of disorder on superfluid 3He, one of an important class of quantum fluids that includes high temperature superconductors. These systems exhibit a high degree of fragility, that is, they have extreme sensitivity to all forms of imperfection and impurities. Investigation of disorder is crucial to their basic understanding and to a realization of their potential for applications. 3He is an ideal choice to study such effects since its pure state is well understood. This is in contrast to many superconductors which have physical and chemical complexity that is difficult to control. The proposed research includes, thermodynamic and acoustic measurements while systematically controlling disorder introduced with highly porous silica aerogel. The work is relevant to theoretical models for neutron star matter, quark Cooper pairs, and exotic vortex states for which 3He is often a reference point. Undergraduate students will participate in the proposed research using phase modulation acoustics and second sound propagation. Training of graduate students in the technically sophisticated areas of magnetic resonance, low-temperature methods, and high frequency acoustics will prepare them for a range of professional career opportunities with a significant potential impact to our society.

该项目将研究疾病对超氟3HE的影响，这是一类重要的量子流体之一，其中包括鲜明的超导体，重型费米昂超导体和高温超导体。 这些非常规系统是由BCS州的Fermions对形成的。 它们都具有超出规格对称性的自发断裂对称性的共同重要特征。 因此，它们对杂质效应特别敏感，如果要了解这些系统的潜在行为，并且是否要实现其应用的潜力，则必须研究。 拟议的研究将带来精确的实验工具，横向高频声学，热容量和薄膜方法，可在气凝胶玻璃中3HE，以确定秩序参数抑制和低较低的激发的密度，并与最新的理论预测相比，用于无差异超导率。 结果将对非常规的超导体，玻色网凝结和外来涡流物质具有广泛的影响。 研究生参与这项工作将为他们提供与基础研究和工业利益有关的技术培训。 关于声学的本科项目将提供与教室相辅相成但外部学习的机会。该项目将研究疾病对超氟3HE的影响，这是包括高温超导体在内的重要类别的量子流体。 这些系统表现出高度的脆弱性，也就是说，它们对所有形式的不完美和杂质具有极大的敏感性。 对疾病的研究对于他们的基本理解和对应用潜力的实现至关重要。 3HE是研究这种效果的理想选择，因为它的纯状态已被充分理解。 这与许多具有难以控制的物理和化学复杂性的超导体相反。 拟议的研究包括热力学和声学测量，同时使用高度多孔的二氧化硅气凝胶引入系统控制障碍。 这项工作与中子恒星物质，夸克·库珀对和外来涡流状态的理论模型相关，而3HE通常是参考点。 本科生将使用相位调制声学和第二个声音传播参加拟议的研究。 培训研究生在磁共振，低温方法和高频声学方面的技术复杂领域的培训将使他们为一系列职业生涯的机会做好准备，并对我们的社会产生重大影响。