Angular position of nodes in the superconducting gap of quasi-2D heavy-fermion superconductor CeCoIn5 - art. no. 057002

The thermal conductivity of the heavy-fermion superconductor CeCoIn5 has be en studied in a magnetic field rotating within the 2D planes. A clear fourf old symmetry of the thermal conductivity which is characteristic of a super conducting gap with nodes along the (+/- pi, +/- pi) directions is resolved . The thermal conductivity measurement also reveals a first-order transitio n at H-c2, indicating a Pauli limited superconducting state. These results indicate that the symmetry most likely belongs to d(x2-y2), implying that t he anisotropic antiferromagnetic fluctuation is relevant to the superconduc tivity.