Anomalous quasiparticle transport and superclean superconducting state of CeCoIn₅

To investigate the quasiparticle dynamics in the superconducting state of quasi-two dimensional heavy fermion superconductor CeCoIn₅, thermal conductivity tensor is measured. We obtained the quasiparticle mean free path and the density of states separately by using the combination of longitudinal thermal conductivity and thermal Hall angle. The quasiparticle mean free path increases dramatically below T_c in zero magnetic field. The density of states and the scaling relation of thermal Hall conductivity are consistent with d-wave symmetry. We also argue that CeCoIn₅ is in the superclean regime. These results highlight the anomalous superconducting state in CeCoIn₅ with striking similarities with high-T_c cuprates.