Order Parameter Structure in Thin Films and Disordered Superfluid 3He

本项目将研究无序对超流3He的影响，超流3He是一类重要的量子流体，包括Ruthenate超导体、重费米子超导体和高温超导体。这些非常规系统是由处于BCS态的费米子对形成的。它们都有一个共同的重要特征，即超越规范对称性的自发破缺对称性。因此，它们对杂质效应特别敏感，如果要了解这些系统的基本行为，如果要实现它们的应用潜力，就必须研究杂质效应。这项拟议的研究将为气凝胶玻璃中的3He提供精确的实验工具，横向高频声学、热容和薄膜方法，以确定有序参数抑制和低激发态密度，并与最近对无间隙超导电性的理论预测进行比较。这些结果将对非传统超导体、玻色-爱因斯坦凝聚和奇异涡旋物质产生广泛的影响。研究生参与这项工作将为他们提供与基础研究和产业兴趣相关的技术培训。声学专业的本科生项目将为学生提供与课堂之外相辅相成的学习机会。这个项目将研究无序对超流3He的影响，超流3He是包括高温超导体在内的一类重要的量子流体。这些系统表现出高度的脆弱性，也就是说，它们对所有形式的缺陷和杂质都非常敏感。对无序的研究对于它们的基本理解和应用潜力的实现是至关重要的。3他是研究这种效应的理想选择，因为它的纯态是众所周知的。这与许多超导体形成鲜明对比，因为它们的物理和化学复杂性很难控制。拟议的研究包括热力学和声学测量，同时系统地控制高孔二氧化硅气凝胶引入的无序。这项工作与中子星物质、夸克库珀对和奇异涡旋态的理论模型有关，3He通常是这些涡旋态的参照点。本科生将使用相位调制声学和二次声传播来参与拟议的研究。对研究生进行磁共振、低温方法和高频声学等尖端技术领域的培训，将使他们为一系列对我们的社会具有重大潜在影响的职业职业机会做好准备。

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.