Calorimetric study of single-crystal CsFe2As2.

We measured the resistivity and the specific heat of CsFe2As2 single crystals, which were grown by using a self-flux method. The CsFe2As2 crystal shows a sharp superconducting transition at 1.8 K with a transition width of 0.1 K. The sharp superconducting transition and pronounced jump in specific heat indicate high quality of the crystals. A large ΔCp/Tc accompanying a very low Tc, nonexponential dependence of the lowest temperature ΔCp/ T and an H1/2 dependence of Δγ(H) are observed in the superconducting-state specific heat; Combined with the fitting results by the α model for the superconducting-state specific heat, a pairing symmetry with nodal gaps was suggested in CsFe2As2. [ABSTRACT FROM AUTHOR]