Superconducting Properties of Ca sub( 3)T sub( 4)Sn sub( 13) (T = Co, Rh, and Ir)

We present the results of the superconducting properties of ... with quasi skutterudite structure by means of magnetic susceptibility, electrical resistivity, and specific heat measurements. It is shown that the superconductivity is of conventional s-wave type and lies in the extremely strong-coupling regime. Electron-phonon coupling constants ... were estimated to be almost 1 for ..., respectively. The result can be categorized as a strong-coupling superconductor; this categorization is in good agreement with the results of specific heat measurements. The ... and the electronic density of states at the Fermi level ... increases with the superconducting transition temperature. However, superconducting transition temperature of Co-compound cannot be explained by the difference of ... From these results, we concluded that ... can be described by the strength of the ... (ProQuest: ... denotes formulae/symbols omitted.)