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تسجيل مستخدم جديدCaPtAs: a new noncentrosymmetric superconductor
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We report the discovery of a new noncentrosymmetric superconductor CaPtAs. It crystallizes in a tetragonal structure (space group $I4_1md$, No.109), featuring three dimensional honeycomb networks of Pt-As and a much elongated $c$-axis ($a = b = 4.18 $ AA, and $c = 43.70 $ AA). The superconductivity of CaPtAs with $T_c$ = 1.47 K was characterized by means of electrical resistivity, specific heat, and ac magnetic susceptibility. The electronic specific heat $C_mathrm{e}(T)/T$ 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 $mu_0H_{c2}$ of CaPtAs exhibits a relatively large 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-5$d$ and As-4$p$ 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.
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By employing a series of experimental techniques, we provide clear evidence that CaPtAs represents a rare example of a noncentrosymmetric superconductor which simultaneously exhibits nodes in the superconducting gap and broken time-reversal symmetry
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