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Theoretical search for quantum intermediate phases in condensed matters

凝聚态物质中量子中间相的理论探索

基本信息

批准号：
15540339
负责人：
IKEDA Ryusuke
金额：
$ 0.83万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

In this research project, we have theoretically studied a couple of quantum condensed matter systems which may include a kind of quantum intermediate state at low temperatures. The subjects we have chosen are in the following ;1)Identifying theoretically the A-like phase of superfluid Helium-three in aerogel,2)Examining a possibility of a quantum metallic phase (Bose-metal) in disordered granular superconductors,3)Understanding effects of fluctuation on the phase transition between the normal and FFLO phases.In 1),motivated by recent experimental facts on liquid Helium-three in aerogels, we have examined how the pairing symmetry and the superfluid long range order in the A-phase are affected by the random scattering events of quasiparticles provided by the aerogel. Through free energy calculations based on the conventional microscopic analysis, we have shown that, as far as the aerogel has no global anisotropy, the ABM pairing state of the bulk A-phase is unaffected by the aerogel, and … More that, as far as the disorder is weak enough, the resulting A-like phase is a superfluid-glass with quasi long-ranged superfluid order. These research results were reported in two papers published in the Physical Review.In 2),inspired by a proposal that the resisitvity remains finite in a glass phase at zero temperature peculiar to the granular systems, we have examined a possibility of a quantum metallic phase in disordered granular superconductors. Our conclusion is negative on this respect : We find that the resistivity in the glass phase of granular systems is zero in agreement with the conventional wisdom on this issue. Due to this conclusion, no reliable theory favoring the presence of a quantum bole - metal phase is present.In 3),an origin of the first - order transition behavior between the normal and the FFLO state in the heavy-fermion superconductor CeCoIn5 was discussed. We have shown on a firm evidence that the discontinuous nature of the normal to FFLO transition is of the mean-field character and not due to the critical fluctuation. Less

在本研究项目中，我们从理论上研究了几个在低温下可能包含一种量子中间态的量子凝聚态系统。我们选择的主题如下：1）从理论上确定气凝胶中超流氦-3的类A相，2）检查量子金属相的可能性（玻色-金属）在无序颗粒超导体中的作用; 3）理解涨落对正常相和FFLO相之间相变的影响。我们研究了气凝胶提供的准粒子的随机散射事件如何影响A相中的配对对称性和超流长程有序。通过基于常规微观分析的自由能计算，我们已经表明，只要气凝胶没有全局各向异性，体A相的ABM配对状态不受气凝胶的影响， ...更多信息只要无序足够弱，所产生的类A相是具有准长程超流有序的超流玻璃。这些研究结果发表在《物理评论》上的两篇论文中。在2）中，受颗粒系统特有的在零温度下玻璃相的介电常数保持有限的提议的启发，我们研究了无序颗粒超导体中量子金属相的可能性。在这方面，我们的结论是否定的：我们发现，在颗粒系统的玻璃相的电阻率为零，在这个问题上与传统的智慧。在3）中，我们讨论了重费米子超导体CeCoIn_5中正常态和FFLO态之间一级跃迁行为的起源。我们已经证明了一个坚实的证据，正常的FFLO过渡的不连续性的性质是平均场的字符，而不是由于临界涨落。少