Understanding the role of strong coupling in quasi-two-dimensional cage type superconductors BaIr2Ge7, Ba3Ir4Ge16 and Ba3Rh4Ge16

Systems that exhibit a high degree of anisotropy have been attracting considerable attention due to unique physical properties. Recently three superconductors (SC), BaIr2Ge7, Ba3Ir4Ge16, and Ba3Rh4Ge16 have reported with transition temperature 3.2 K, 6.1 K, and 6.5 K, respectively. These compounds share unique quasi-two-dimensional networks composed of crown shaped Ge rings that accommodate Ba atoms at the center, referred to as “edge-shared crown-shaped BaGe16 polyhedra”. The Ba-Ge structural unit is similar to cage structures seen in various clathrates which are example of strong-coupling SC. In these systems the superconducting order parameter is much stronger in the ab plane than in the c-direction, hence indicates quasi-two-dimensional nature. In this proposal, we intend to investigate the TF/ZF musr to explore the superconductivity in the quasi-two-dimensional compounds.具有高度各向异性（anisotropy）的体系因其独特的物理性质一直备受关注。近期，三种超导体（SC）——BaIr₂Ge₇、Ba₃Ir₄Ge₁₆和Ba₃Rh₄Ge₁₆——被报道其转变温度分别为3.2 K、6.1 K和6.5 K。这些化合物具有独特的准二维网络结构，由冠状Ge环构成，环中心容纳Ba原子，该结构被称为"边共享冠状BaGe₁₆多面体"。Ba-Ge结构单元与多种笼合物中的笼状结构相似，而笼合物是强耦合超导体（SC）的典型例子。在这些体系中，超导序参量在ab平面的强度远高于c方向，因此体现出准二维特性。本研究计划旨在通过TF/ZF缪子自旋弛豫（musr）研究来探索这些准二维化合物中的超导性。