Thermal conductivity tensor of single crystalline Co-doped BaFe2As2

Thermal conductivity tensor has been measured using single crystalline Co-doped BaFe2As2 down to 0.1 K and under magnetic fields up to 7 T. We observe peak anomalies both in the thermal conductivity and the thermal Hall conductivity in the superconducting state as an indication of enhancement of the quasiparticle mean-free path. Furthermore, we find a residual T-linear term in the thermal conductivity possibly due to a finite quasiparticle density of states in the superconducting gap induced by impurity pair-breaking.