Detailed Characterization of U–Co Binary Compounds

We have measured the electrical resistivity and specific heat to 0.3 K on a Czochralski-grown single crystal of UCo. The electrical resistivity shows superconductivity below T c ∼1.9 K but with a small associated specific heat anomaly, as earlier reported for polycrystalline material. We determined that the superconductivity in our crystal arises from inclusion of impurity U 6 Co, and that UCo is a non-superconducting paramagnet down to 0.3 K with an electronic specific heat coefficient γ of 4.5 mJ/K 2 ·mol.