CaPtAs: A new noncentrosymmetric superconductor

Abstract

We report the discovery of a new noncentrosymmetric superconductor CaPtAs.It crystallizes in a tetragonal structure (space group I41md, No. 109), featuring three dimensional honeycomb networks of Pt-As and a much elongated c-axis (a = b = 4.18 Å and c = 43.70 Å .The superconductivity of CaPtAs with Tc = 1.47 K was characterized by means of electrical resistivity, specific heat, and ac magnetic susceptibility.The electronic specific heat Ce(T)/T shows evidence for a deviation from the behavior of a conventional BCS superconductor, and can be reasonably fitted by a p-wave model.The upper critical field μ0Hc2 of CaPtAs exhibits a moderate anisotropy, with an in-plane value of around 204 mT and an out-of-plane value of 148 mT.Density functional theory calculations indicate that the Pt-5d and As-4p orbitals mainly contribute to the density of states near the Fermi level,showing that the Pt-As honeycomb networks may significantly influence the superconducting properties.