Unconventional superconductivity in CeIrIn₅ and CeCoIn₅: Specific heat and thermal conductivity studies

Low temperature specific heat and thermal conductivity measurements on the ambient pressure heavy fermion superconductors CeIrIn5 and CeCoIn5 reveal power law temperature dependences of these quantities below T$_c$. The low temperature specific heat in both CeIrIn5 and CeCoIn5 includes T$^2$ terms, consistent with the presence of nodes in the superconducting energy gap. The thermal conductivity data present a T-linear term consistent with the universal limit (CeIrIn5), and a low temperature T$^3$ variation in the clean limit (CeCoIn5), also in accord with prediction for an unconventional superconductor with lines of nodes.