Superconductivity in Y2C3 with medium Tc

Recently, we have reported a relatively high-Tc superconductivity in Y2C3 at 18 K whose Tc could be changed by synthesis conditions from 10 to 18 K [G. Amano, S. Akutagawa, T. Muranaka, Y. Zenitani, J. Akimitsu, Superconductivity at 18 K in yttrium sesquicarbide system, Y2C3J. Phys. Soc. Jpn. 73 (2004) 530.]. We synthesized a high-purity sample of the medium-Tc phase in Y2C3 and examined its physical properties in detail. From a specific heat measurement, ΔC(Tc)/γTc value is calculated to be 6.50 and the superconducting gap is estimated to be 2Δ/kBTc=5.40, indicating that the superconductivity in Y2C3 can be described by an s-wave strong coupling regime.