在(Ca,Na)Fe2As2 体系中得到Tc>33K的超导转变

 (Superconductivity above 33 K in (Ca1-xNax)Fe2As2)

K. Zhao, Q.Q. Liu, X.C. Wang, Z. Deng, Y.X. Lv, J.L. Zhu, F.Y. Li and C.Q. Jin

J. Phys.: Condens. Matter 22, 222203 (2010) (Fast Track Communication)

 　　　在"122"型铁基超导体系中，最佳掺杂Ba-122和Sr-122的最高超导转变温度约为38K和35K，而Ca-122的超导转变温度最高报道约为20K（ (Ca0.5Na0.5)Fe2As2）。我们通过进一步提高Ca-122的掺杂浓度，制备出(Ca0.33Na0.66)Fe2As2单晶样品，其超导转变温度大于33K。

　　We report the synthesis of (Ca0.33Na0.66)Fe2As2 showing a superconducting transition with Tc above 33 K. Both dc magnetic susceptibility and specific heat measurements indicated the bulk superconductivity nature of the sample. We also have successfully grown single crystals of the (Ca0.33Na0.66)Fe2As2 superconductors. The single crystals exhibit sharp superconducting transitions with Tc above 33 K. The effects of magnetic field on the superconducting transitions are studied, giving rise to high upper critical fields with Hc2(c) ≈ 85 T and Hc2(ab) ≈ 172 T, respectively. The anisotropy parameter was calculated to be around 2.