Thermal conductivity of a heavy fermion superconductor UPd2Al3 single crystal

We have studied the thermal conductivity kappa and electrical resistivity rho of UPd2Al3 single crystal in the temperature range between 0.36 K and 70 K in magnetic fields up to 5 T. At high temperatures, the thermal conductivity is dominated by phonons. Below the Neel temperature T-N = 14.5 K, kappa, shows an enhancement compared with the extrapolated behavior from the higher temperature than TN, which is associated with the steep decrease of rho. This suggests the increase of the electron contribution to kappa below T-N due to the decrease of the magnetic scattering. The temperature dependence of kappa does not show an anomaly at T-c and shows a T-2 behavior below 1 K, which suggests that the superconducting gap in UPd2Al3 vanishes along lines on the Fermi surface. kappa in magnetic field shows clearly a larger decrease below T-c than above T-c with decreasing temperature, which is very different from the temperature dependence of kappa in zero magnetic field.