THERMAL-CONDUCTIVITY OF HEAVY-FERMION SUPERCONDUCTOR URU2SI2

The thermal conductivity of a URu2Si2 single crystal was studied as a function of temperature (between 40 mK and 2 K) and magnetic field (up to 7 T). At the onset of superconductivity, the electronic contribution counts roughly for half the overall thermal conductivity revealing an important lattice contribution. An electron-phonon coupling parameter is found which is much smaller than that for conventional superconductors. The field dependence of the thermal conductivity at various temperatures is highly anisotropic and confirms the presence of multiple types of heat carriers.