Carbon isotope effect in superconducting MgCNi3 -: art. no. 212514

The effect of carbon isotope substitution on T-C in the intermetallic perovskite superconductor MgCNi3 is reported. Four independent groups of samples were synthesized and characterized. The average T-C for the C-12 samples was found to be 7.12+/-0.02 K and the average T-C for the C-13 samples was found to be 6.82+/-0.02 K. The resulting carbon isotope effect coefficient is alpha(C)=0.540+/-0.03. This indicates that carbon-based phonons play a critical role in the presence of superconductivity in this compound.