Features of heat transport in organic and cuprate superconductors

Thermal conductivity measurements in the cuprates have established two unusual and distinct features of quasi-particle transport in the superconducting state. Both these features (i.e. the abrupt increase in the relaxation time at the onset of superconductivity and a finite zero-energy transport due to presence of nodes in the superconducting gap) may also be present in kappa - (ET)(2)Cu(NCS)(2) according to the first study of heat transport in this two-dimensional organic superconductor. In the case of optimally-doped Bi-2212, the modification of low-temperature thermal conductivity by the introduction of point defects was investigated. Results provide new information on the structure of low-energy electronic excitations of the superconducting state.