Single Crystal Growth and Anisotropy of the Upper Critical Field of CeIr₃

Abstract

We present single crystal growth of Ce-based superconductor CeIr 3 with the intermediate valence state and report on the anisotropy of the upper critical field H c2. CeIr 3 crystallizes in the PuNi 3type rhombohedral structure with the space group R3m and shows a superconducting transition at T c = 3.4 K. We investigated the temperature and field-angle dependence of H c2 , obtained by the electrical resistivity measurements using CeIr 3 single crystals. The temperature dependence of H c2 is well described by a two-gap superconductivity model for the magnetic field H || c-axis, while H c2 (T) cannot be explained by the Werthamer-Helfand-Hohenberg (WHH) model. Furthermore, the fieldangle dependence of H c2 for H || a-axis shows a characteristic cusp-like feature, deviating from the conventional three-dimensional (3D) effective mass model and the two-dimensional (2D) Tinkham model.

Impact of the Ce 4f states in the electronic structure of the intermediate-valence superconductor CeIr3

“…Single crystals of CeIr 3 were prepared using the Czochralski method in a tetra arc furnace under Ar atmosphere. The details of the sample growth and their characterizations were presented in [1,3,11]. Photoemission experiments were performed at the soft x-ray beamline BL23SU of SPring-8 [12].…”