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种可能包含低温下量子中间态的量子凝聚态系统，我们选择的主题如下：1）从理论上识别超流体的A类相。气凝胶中的氦三，2) 检查无序粒状超导体中量子金属相（玻色金属）的可能性，3) 了解涨落对正常和 FFLO 之间相变的影响在1）中，受气凝胶中液氦三的最新实验事实的启发，我们研究了A相中的配对对称性和超流体长程有序性如何受到气凝胶提供的准粒子随机散射事件的影响通过基于常规微观分析的自由能计算，我们表明，只要气凝胶不具有整体各向异性，体相A相的ABM配对状态为。不受气凝胶的影响，并且......更多的是，只要无序足够弱，所得的类A相是具有准长程超流体有序的超流玻璃。这些研究结果发表在《物理》杂志上的两篇论文中。回顾。在2）中，受颗粒系统特有的零温度玻璃相中电阻率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。我们的结论在这方面是否定的：我们发现粒状系统的玻璃相的电阻率为零，与这个问题上的传统观点一致，由于这个结论，没有可靠的理论支持量子金属相的存在。在3）中，讨论了重费米子超导体CeCoIn5中正常状态和FFLO状态之间的一阶跃迁行为的起源，我们已经证明了正常状态到FFLO状态的不连续性质。 FFLO 转变具有平均场特征，而不是由临界波动引起。