Exotic properties in the filled skutterudite compounds and their control by uniaxial pressure

我们一直在努力生长REFe_4P_<12>，RERu_4Sb_<12>，REOs_4Sb_<12>（RE=La，Ce，Pr，Nd）的大尺寸高质量单晶。在生长的晶体上，我们测量了基本的物理性质，并与许多研究小组合作研究了各种重要性质，其中，我们简要报告了最重要的部分，特别是Pr基系统。(1)μ <12>SR测量进一步证实了PrFe_4P_3：非磁性CEF基态。仔细评估的铁磁和反铁磁组件在低温有序状态下的中子散射实验在低温下的磁场揭示的相位是一个四极。此外，有序状态被发现是不稳定的，对由La从运输，磁性和比热测量的Pr的替代。(2)PrOs_4Sb_<12>：根据de Haas-van Alphen（dHvA），发现其费米面与参比化合物LaOs_4Sb_的费米面接近，反映了PrOs_4Sb_<12>的 ...更多信息 F-电子的局域化性质，同时我们证实了预期来自C-F杂化的高度增强的有效质量。在核磁共振实验中，既没有观察到超导带隙中的相干峰，也没有观察到超导带隙中的节点结构。相反，从磁场中热导率的角度依赖性来看，各向异性间隙具有点节点。此外，在超导相中还发现了两种不同对称性的相。通过对比热和磁化强度的系统测量和分析，发现Γ_1是最可能的CEF基态。(3)PrRu_4P_<12>：它是一种1^<st>Pr基填充方钴矿，具有非磁性的金属-绝缘体转变，并提出了一种嵌套模型（NM）。然而，目前还没有澄清任何事情。我们成功地检测到dHvA信号，并确定了FS。我们还进行了第一次成功的输运和比热实验，这表明只有NM不能解释M-I跃迁。少

We have kept trying to grow large and high quality single crystals of REFe_4P_<12>, RERu_4Sb_<12>, REOs_4Sb_<12> (RE=La, Ce, Pr, Nd). On the grown crystals, we have measured basic physical properties and have made cooperative researches on various important properties with many research groups.Among them, we briefly report the most important part, especially on Pr-based systems.(1) PrFe_4P_<12> : Non-magnetic CEF ground state was further confirmed by μSR measurement. A careful evaluation of the ferro- and antiferro-magnetic components in the low temperature ordered state by neutron scattering experiments at low temperatures under magnetic fields revealed the phase to be a quadrupole one. Furthermore, the ordered state was found to be unstable against a replacement of Pr by La from transport, magnetic and specific heat measurements.(2) PrOs_4Sb_<12> : From de Haas-van Alphen (dHvA), its Fermi surface was found to be close to that of the reference compounds LaOs_4Sb_<12>, reflecting the … More localized nature of f-electrons, while we confirmed highly enhanced effective mass expected from c-f hybridization. In a NMR experiment, neither coherence peak nor node structure in superconducting gap has been observed. On the contrary, from the angular dependence of thermal conductivity in magnetic fields, anisotropic gap with point nodes. In addition, there found two different phase with different symmetries in the superconducting phase. From systematic measurements and analyses of specific heat and magnetization, Γ_1 was found to be the most probable CEF-ground state.(3) PrRu_4P_<12> : It is the 1^<st> Pr-based filled skutterudite exhibiting interesting feature (non-magnetic metal-insulator transition) and a nesting model (NM) was proposed to be an origin. However, nothing has been clarified yet. We have succeeded in detecting dHvA signal, and determined the FS. We have also performed the first successful transport and specific heat experiment, which suggests only the NM cannot explain the M-I transition. Less