  Experimental and theoretical studies on superconductivity in SrIr$_2$ and
SrRh$_2$ Laves phases are presented. The measured resistivity, heat capacity,
and magnetic susceptibility confirm the superconductivity of these compounds
with $T_c$ = 6.07 K and 5.41 K, respectively. Electronic structure calculations
show that the Fermi surface is mostly contributed by 5$d$ (4$d$) electrons of
Ir (Rh), with Sr atoms playing the role of electron donors. The effect of the
spin-orbit coupling is analyzed and found to be important in both materials.
Lattice dynamics and electron-phonon coupling (EPC) are studied and the strong
electron-phonon interaction is found, contributed mostly by the low-frequency
Ir and Rh vibrations. The enhancement of EPC when compared to weakly-coupled
metallic Ir and Rh is explained by the strong modifications in the propagation
of phonons in the network of Ir (Rh) tetrahedrons, which are the building
blocks of the Laves phase, and originate from the metallic fcc structures of
elemental iridium and rhodium.
