Thermodynamic, magnetic and transport properties of Rh₁₇S₁₅

We determined thermodynamic (specific heat), magnetic (magnetization, magnetostriction and susceptibility) and transport (electrical resistivity) properties of the 4d-electron superconductor Rh₁₇S₁₅ (T_c = 5.3 K). The upper critical field is 19.2 T at T = 0.07 K. We investigated both a polycrystal and a single crystal. Specific heat gives (B = 0) = 107 mJ/molK², m_eff = 35 m₀, and a superconducting energy gap Δ₀ = 0.94 meV. The magnetic properties are dominated by flux-line pinning; resistivity likely reveals an amplification of electron-phonon coupling by weak disorder. Additionally, band-structure calculations are presented and interpreted in the context of our own experiments and other recently published results.We interpret our findings in order to find the origin of the strong electronic correlations in Rh₁₇S₁₅ both in the superconducting and in the normal-conducting state.