The effect of chemical substitution in Rh₁₇S₁₅

Abstract

Rh₁₇S₁₅ has recently been shown to be a strongly correlated superconductor with a transition temperature of 5.4 K. In order to understand the nature of the strong correlations we study the effect of replacement of some of the Rh and S atoms by other elements such as Fe, Pd, Ir and Ni on the Rh side and Se on the S side in this work. We find that while replacements of Ir and Se lower the transition temperature considerably, those of Fe, Pd and Ni destroy the superconductivity down to 1.5 K. The resistivity data for these doped samples show a minimum which is presumably disorder induced. A reduction of T_c is always accompanied by a reduction of electron correlations, as deduced from heat capacity and magnetization data. Interestingly, the Fe doped sample shows evidence of spin glass formation at low temperatures.