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TT: Fachverband Tiefe Temperaturen

TT 9: SC: Poster Session

TT 9.36: Poster

Montag, 22. März 2010, 14:00–18:00, Poster A

Superconducting Phase Diagram of Rh₁₇S₁₅ — •M. Uhlarz¹, O. Ignatchik¹, J. Wosnitza^1,3, R. Daou², M. Doerr³, A. Haase^1,3, H.R. Naren⁴, A. Thamizhavel⁴, and S. Ramakrishnan⁴ — ¹Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf, 01314 Dresden — ²Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden — ³Institut für Festkörperphysik, TU Dresden, 01069 Dresden — ⁴Tata Institute of Fundamental Research, Mumbai-400005, India

Rh₁₇S₁₅ is a 4d-electron metal which becomes superconducting below T_c = 5.4 K at zero field. The upper critical field is 19.2 T at T = 0.07 K. Above T_c, Rh₁₇S₁₅ is a paramagnet. The crystallographic structure (Pm3m) of Rh₁₇S₁₅ features a nearest-neighbor Rh-Rh distance even less than in elementary (fcc) Rh, possibly resulting in a high density of 4d-electron states at the Fermi level.

Using a polycrystalline sample, we measured the specific heat, resistivity, magnetisation, and magnetostriction in fields up to 14 T as well as the magnetic susceptibility in fields up to 20 T. Our data allow us to present the complete superconducting phase diagram. The assumption of narrow 4d band states (and thus of strong electronic correlations not providing magnetic correlations) is supported by the moderately enhanced electronic contribution to the specific heat of 107 mJ/molK² and favors the existence of a strong superconducting interaction. Together with the remarkably high upper critical field (exceeding the Pauli limit by a factor of two), our findings make Rh₁₇S₁₅ a likely candidate for unconventional superconductivity.