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 Delta C-p/T-c accompanying a very low T-c, nonexponential dependence of the lowest temperature Lambda C-p/T and an H-1/2 dependence of Lambda gamma(H) are observed in the superconducting-state specific heat. Combined with the fitting results by the alpha model for the superconducting-state specific heat, a pairing symmetry with nodal gaps was suggested in CsFe2As2.