Ordered Phases of Solid and Liquid Helium Three

固氦和液氦三的有序相

• 批准号: 9110423
• 负责人: Douglas Osheroff
• 金额: $ 39.05万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-07-01 至 1994-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9110423&HistoricalAwards=false
• 关键词: Ordered; Phases; Solid; Liquid; Helium

Quantum fluids and solids have served as important topics of research in their own right, and as model systems for understanding similar physical phenomena exhibited in more complex materials. They propose here three series of experiments intended to further their physical understanding in both these regards. The first series will involve ultrasound studies of the U2D2 phase of solid 3He with the intention of searching for the lattice distortion expected to occur upon nuclear spin ordering, and to more fully measure the magnetic Gruneisen tensor. These studies shoud help answer a number of remaining fundamental questions regarding this model magnetic system. The second series will involve a search for superfluidity in two dimensional sub-monolayer films of 3He adsorbed on top of 2-4 monolayer films of superfluid 4He. If successful, this search will provide us with an entirely new BCS superfluid state, which should shed light on possible 2D superconducting states. Finally, they will investigate the process by which the B-phase of superfluid 3He is nucleated from the A- phase superfluid. This seemingly simple problem is a particularly tempting one because we know so much about these phases that they feel they should be able to fully understand this transition. Further, the relevant length scale of the A to B nucleation is so long that this transition represents a rare opportunity to understand in equisite detail inhomogeneous nucleation at a first order phase transition.

量子流体和量子固体本身已经成为重要的研究课题，并作为模型系统来理解在更复杂的材料中表现出的类似物理现象。他们在这里提出了三个系列的实验，旨在进一步加深他们在这两个方面的物理理解。第一个系列将涉及固体3He的U2D2相的超声研究，目的是寻找核自旋排序时可能发生的晶格畸变，并更全面地测量磁性Gruneisen张量。这些研究应该有助于回答一些关于这个模型磁系统的基本问题。第二个系列将涉及寻找吸附在2-4超流体4He单层膜上的二维亚单层3He膜中的超流动性。如果成功，这项研究将为我们提供一个全新的BCS超流体状态，这将有助于揭示可能的二维超导状态。最后，他们将研究超流体3He的b相从A相超流体成核的过程。这个看似简单的问题是一个特别诱人的问题，因为我们对这些阶段知道得太多了，他们觉得他们应该能够完全理解这个转变。此外，A到B成核的相关长度尺度是如此之长，以至于这种转变代表了一个难得的机会，可以在相当详细的情况下了解一级相变的非均匀成核。