Phisics of Strongly Correlated Conducting Elevtrons

强相关传导电子的物理学

• 批准号: 06244104
• 负责人: SHIBA Hiroyuki
• 金额: $ 28.67万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06244104/
• 关键词: superconductivity; heavy fermious; non-fermi liquid; quadrunpole ordering; Kondo effect; Kondo semiconductor; band structure calculation; uranium compound; 四重極子秩序; 近藤絶縁体; 四重極近藤効果; バンド理論; 異常ホール効果

The Theory Group of Research Project "Physics of Strongly Correlated Conducting Electrons" has carried out research in close collaboration with the Experiment Group. The main results during the 4 years are as follows.(1) Among many f-electron superconductors UPt3 having plural superconducting phases is clearly unconventional in the nature of superconductivity. On this material Kitaoka et. al. (Osaka Univ.) and Sakakibara (Hokkaido Univ.) have carried out detailed NMR and magnetic measurements. Machida (Okayama Univ.) has proposed a scenario of triplet superconductivity to explain those experiments based on a phenomenological theory. It is the next important problem to give a microscopic origin of the superconductivity.(2) It is a common wisdom that magnetic impurities in metals usually turn to Fermi liquid at low temperatures. However, Sakakibara et. al. found that ThRuィイD22ィエD2SiィイD22ィエD2 containing dilute U shows non-Fermi liquid behavior. This problem was theoretically studied by 3 … More groups, Shiba (Tokyo Inst. Tech.), Sakai (Tohoku Univ.) and Miyake (Osaka Univ.). The results show that when the crystal field ground state is non-Kramers doublet and well separated from excited states, two-channel-Kondo non-Fermi liquid is possible, while it is taken over by Fermi liquid when the excited states become low. Sakai and his coworkers determined the temperature dependence of various physical quantities by using numerical renormalization group method.(3) Because of orbital degrees of freedom the ordered phase of some f-electron systems are complicated. In addition to ordinary magnetic orderings one can have an ordered phase related to quadrupole moments. CeBィイD26ィエD2 a typical example of this sort. The nature of the ordered phase in magnetic fields in particular had been a matter of controversy. Shiba and Sakai studied this problem and showed that in CeBィイD26ィエD2 the field-induced octupoles are sizable and important to explain the NMR shifts, which had been a mystery for a long period. In this connection Kuramoto (Tohoku Univ.) presented a theory of fluctuating quadrupoles.(4) Miyake presented a theory of Kondo semiconductors, taking into account the k-dependence of mixing matrix elements. It explains well experimental results of CeNiSn, which Takabatake (Hiroshima Univ.) studied experimentally.(5) Band structure calculations have been carried out on many rare-earth compounds by Hasegawa (Niigata Univ.) and Harima (Osaka Univ.). They have brought important information on electronic structure through a comparison with de Hans- van Alphen experiments by Onuki (Osaka Univ.). Hasegawa et. al. have develped a theory of relativistic current and spin density functional. It is hoped that it is successfully applied to actinide compounds. Less

研究项目"强关联导电电子物理学"的理论组与实验组密切合作开展了研究。四年来的主要成果如下。(1)在许多具有多个超导相的f电子超导体中，UPt3在超导性的本质上显然是非常规的。在这种材料Kitaoka et.（Osaka Univ.）和Sakakibara（北海道大学）进行了详细的核磁共振和磁性测量。町田（冈山大学）提出了一个三重态超导的方案来解释那些基于唯象理论的实验。下一个重要的问题是给出超导电性的微观起源。(2)人们普遍认为，金属中的磁性杂质通常在低温下变成费米液体。然而，Sakakibara et.等人发现，含有稀U的ThRu双金属D22双金属D2Si双金属D22双金属D2显示非费米液体行为。本文从理论上对这一问题进行了研究， ...更多信息 集团，芝（东京工业大学），酒井（东北大学）和Miyake（大坂大学）。结果表明，当晶体场基态为非Kramers二重态且与激发态分离较好时，双通道近藤非费米液体是可能的，而当激发态较低时，双通道近藤非费米液体被费米液体取代. Sakai和他的同事们用数值重整化群方法确定了各种物理量对温度的依赖关系。(3)由于轨道自由度的存在，某些f-电子系统的有序相是复杂的。除了普通的磁序，还可以有与四极矩有关的有序相。CeBD26和CeBD2是这类的一个典型例子。特别是磁场中有序相的性质一直是一个有争议的问题。Shiba和Sakai研究了这个问题，并表明在CeBD26中，场致八极子是相当大的，对于解释NMR位移很重要，这在很长一段时间内都是一个谜。在这方面，仓本（东北大学）提出了波动四极子理论(4)三宅提出了近藤半导体理论，考虑到混合矩阵元素的k依赖性。这很好地解释了高岳（广岛大学）实验研究。(5)Hasegawa（新泻大学）对许多稀土化合物进行了能带结构计算。和Harima（大坂大学）。通过与大坂大学Onuki的de Hans-货车Alphen实验的比较，他们带来了关于电子结构的重要信息。长谷川等等人发展了相对论电流和自旋密度泛函理论。希望它能成功地应用于锕系化合物。少

项目成果

Takashi Takahashi: "Crystal-Field Splitting in CeB_6 as Observed by High-Resolution Photoemission." Physical Review. B52. 9140-9142 (1995)

Takashi Takahashi：“通过高分辨率光电发射观察到 CeB_6 中的晶体场分裂。”