Theory of Magnetism and Super-fluid Transition of Liquid He-3

液态He-3磁学与超流转变理论

基本信息

批准号：
11640354
负责人：
NAGAI Katsuhiko
金额：
$ 2.11万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

It is widely accepted that the liquid ^3He undergoes a superfluid phase transition forming p-wave Cooper pairs by aid of so-called paramagnon mediated attractive interaction. This mechanism explains well the stability of the ABM state at higher pressures and temperatures. On the other hand, in the normal state, magnetic properties of liquid ^3He is not well described by the paramagnon theory but rather satisfactory by nearly localized model. Moreover, it is recently reported that in the superfluid ^3He in aerogel, the ABM state does not appear when no magnetic field is applied. It implies that the pairing interaction may change due to the impurity scattering.From these aspects, we have studied (1)the susceptibility of normal liquid ^3He taking into account the spin fluctuation, (2)impurity effects on sound propagation in liquid ^3He in aerogel, (3) Formulation of boundary problem for superfluids and superconductors and its application to surface effect on Meissner diamagnetism of proximity-contact normal superconducting systems. In the study of the susceptibility, we have shown that the Fermi surface singularity gives rise to logarithmic temperature dependence of the susceptibility. In the study of sound in liquid ^3He in aerogel, we found that the motion of aerogel due to the collision drag effect plays a dominant role. We expect this study will contribute to the understanding of impurity effect by aerogel on liquid ^3He and also to the pairing mechanism of liquid ^3He in aerogel. The surface problem is very important in the interpretation of sound propagation, in particular anisotropic superfluid such as ^3He, because the sound is excited by transducers at the surface. We have formulated boundary condition for the quasi-classical theory and now trying to extend the theory such that can handle the dynamical problems.

人们普遍认为，液体 ^3He 借助所谓的顺磁子介导的吸引力相互作用，经历超流体相变，形成 p 波库珀对。这一机制很好地解释了 ABM 状态在较高压力和温度下的稳定性。另一方面，在正常状态下，液体^3He的磁特性不能用顺磁振子理论很好地描述，但用近局域模型可以令人满意。而且，最近有报道称，在气凝胶中的超流体^3He中，在不施加磁场的情况下不会出现ABM状态。这意味着配对相互作用可能会因杂质散射而改变。从这些方面，我们研究了（1）考虑自旋涨落的正常液体^3He的磁化率，（2）杂质对液体中声音传播的影响^3He在气凝胶中，（3）超流体和超导体边界问题的公式化及其在接近接触正常超导系统迈斯纳抗磁性的表面效应中的应用。在磁化率的研究中，我们表明费米表面奇点引起磁化率的对数温度依赖性。在气凝胶中液体^3He中的声音研究中，我们发现气凝胶由于碰撞阻力效应而产生的运动起着主导作用。我们期望这项研究将有助于理解气凝胶对液体^3He的杂质效应以及气凝胶中液体^3He的配对机制。表面问题在解释声音传播时非常重要，特别是各向异性超流体（例如 ^3He），因为声音是由表面的换能器激发的。我们已经为准经典理论制定了边界条件，现在正在尝试扩展该理论以处理动力学问题。