Ordered Phases of Solid and Liquid 3He in Defined Geometries

定义几何形状中固体和液体 3He 的有序相

• 批准号: 0305465
• 负责人: Douglas Osheroff
• 金额: $ 39万
• 依托单位: Stanford 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=0305465&HistoricalAwards=false
• 关键词: Ordered; Phases; Solid; Liquid; 3He

This research focuses on the response of superfluid 3He B to the presence of structures much smaller than the superfluid coherence length, x. These results can serve as a paradigm for understanding how other unconventional BCS states, such as the oxide superconductors, will respond to the presence of impurities. In this work, the bending stiffness of the order parameter will be measured for the first time by growing aerogel within an array of parallel plates. Here the magnetic field competes with surface effects to orient the order parameter. In a separate collaboration with Frank Gasparini of the University of Buffalo, the superfluid 3He density will be studied in channels accurately etched in silicon substrates. This will allow the first accurate measurements of the superfluid gap suppression in well-defined confining geometries. Another experiment will study the mobility of domain walls in U2D2 nuclear spin ordered solid 3He, to see if this system might be a candidate for studying macroscopic quantum tunneling. Graduate students involved in these projects will receive training in ultra-low temperature refrigeration techniques, NMR spectroscopy, and the design of sophisticated apparatus. This training has allowed previous students to go on to successful careers in academia, national laboratories, and industry. %%%This work will study how the scattering of superfluid 3He by strands just 5 nm in diameter in silica aerogels alter the properties of the superfluid. This is a macroscopic quantum state, directly analogous to that in superconductors, particularly the high temperature oxide superconductors. In both cases impurity scattering can destroy the ordered state. By studying how the superfluid is oriented in an aerogel sample grown in the gaps between parallel plates using NMR techniques, it will be possible to measure how this scattering affects the stiffness of the ordered state to bending for the first time. In a separate collaborative study with Frank Gasparini, University of Buffalo, superfluid 3He will be studied in well-defined narrow channels etched in silicon substrates. This will allow an accurate first measurement of the suppression of superfluidity by well defined, highly confining geometries. These results should be useful in understanding how a broad class of superfluids and superconductors will be affected by impurity scattering and confinement, from the high Tc superconductors to the dense matter in neutron stars. Students in this program learn techniques and materials physics that allow them to pursue careers in academe government, and industrial settings.

本研究的重点是响应的超流3He B的结构的存在远远小于超流相干长度，x。 这些结果可以作为理解其他非常规BCS状态（如氧化物超导体）如何响应杂质存在的范例。 在这项工作中，弯曲刚度的序参数将首次通过在平行板阵列内生长气凝胶来测量。 在这里，磁场与表面效应竞争定向序参量。 在与布法罗大学的弗兰克·加斯帕里尼（Frank Gasparini）的单独合作中，将在硅衬底上精确蚀刻的通道中研究超流3He密度。 这将允许第一次精确测量的超流间隙抑制在良好定义的限制几何形状。 另一个实验将研究U2D2核自旋有序固体3He中畴壁的迁移率，看看这个系统是否可能成为研究宏观量子隧穿的候选者。 参与这些项目的研究生将接受超低温制冷技术、核磁共振光谱学和精密仪器设计的培训。 这项培训使以前的学生能够在学术界、国家实验室和工业界继续成功的职业生涯。这项工作将研究如何散射的超流3He线直径仅为5纳米的二氧化硅气凝胶改变超流的性质。 这是一种宏观量子态，直接类似于超导体，特别是高温氧化物超导体。 在这两种情况下，杂质散射可以破坏有序状态。 通过使用NMR技术研究超流体如何在平行板之间的间隙中生长的气凝胶样品中取向，将有可能首次测量这种散射如何影响有序状态的弯曲刚度。 在另一项与布法罗大学的弗兰克·加斯帕里尼的合作研究中，将在硅衬底上蚀刻的定义明确的狭窄通道中研究超流3He。 这将允许精确的第一次测量的抑制超流的定义明确，高度限制的几何形状。 这些结果应该是有用的，在理解如何广泛的超流体和超导体将受到杂质散射和限制，从高Tc超导体的中子星中的致密物质。 该计划的学生学习技术和材料物理学，使他们能够在政府和工业环境中从事职业生涯。