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.