Transport, thermal, and magnetic properties in heavy-fermion superconductor Ce2CoIn8

We have grown high purity single crystals of Ce2CoIn8 using the self-flux technique, and have investigated its transport, thermal, and magnetic properties, including the anisotropic features. Single crystals of Ce2CoIn8 were grown in the lower temperature region to avoid the formation of in-wanted phases such as CeCoIn5 and CeIn3 impurities. The results of the structural and physical measurements imply that the present single crystals have high purity. The electrical resistivity and specific heat measurements demonstrate that Ce2CoIn8 has a superconducting ground state with a distinct non-Fermi liquid character. This indicates that the superconductivity in Ce2CoIn8 arises out of the verge of the underlying quantum critical instability mediated by the antiferromagnetic correlations. Additionally, we investigate the crystalline electric field (CEF) energy scheme based on the temperature dependence of the specific heat and the anisotropic features in the susceptibility. We propose one of the CEF level schemes calculated on the basis of the CEF model that the first and second CEF states are located at Delta(1) = 82 K and Delta(2) = 102 K above the ground state doublet, respectively. (C) 2011 Elsevier B.V. All rights reserved.