Upper critical fields and anisotropy of Ca1-xLaxFe2As2 single crystals

作者：Zhou W^*; Yuan F F; Zhuang J C; Sun Y; Ding Y; Cui L J; Bai J; Shi Z X

来源：Superconductor Science and Technology, 2013, 26(9): 095003.

DOI：10.1088/0953-2048/26/9/095003

The superconductivity of Ca1-xLaxFe2As2 single crystals with various doping levels was investigated via electromagnetic measurements for out-plane (H parallel to c) and in-plane (H parallel to ab) magnetic field directions. Obvious double superconducting transitions, which can survive in magnetic fields up to several tesla, were observed in the medium-doped (x = 0.13) sample. Two kinds of distinct upper critical field (H-c2) phase diagrams were established for the low superconducting phase with T-c lower than 15 K and the high superconducting phase with superconducting transition temperature (T-c) of over 40 K, respectively. Both kinds of phase diagram exist in the medium-doped sample. Unusual upward curvature near T-c was observed in H-c2 phase diagrams and analyzed in detail. Temperature dependences of anisotropy for different doping concentrations were obtained and compared. Both superconducting phases manifest extremely large anisotropies, which may originate from the interface or intercalation superconductivity.

• 出版日期2013-9
• 单位东南大学