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Unusual superconducting state at 49 K in electron-doped CaFe₂As₂ at ambient pressure

We report the detection of unusual superconductivity up to 49 K in single crystalline CaFe₂As₂ via electron-doping by partial replacement of Ca by rare-earth. The superconducting transition observed suggests the possible existence of two phases: one starting at 49 K, which has a low critical field &...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2011-09, Vol.108 (38), p.15705-15709
Main Authors: Lv, Bing, Deng, Liangzi, Gooch, Melissa, Wei, Fengyan, Sun, Yanyi, Meen, James K., Xue, Yu-Yi, Lorenz, Bernd, Chu, Ching-Wu
Format: Article
Language:English
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Summary:We report the detection of unusual superconductivity up to 49 K in single crystalline CaFe₂As₂ via electron-doping by partial replacement of Ca by rare-earth. The superconducting transition observed suggests the possible existence of two phases: one starting at 49 K, which has a low critical field < 4 Oe, and the other at 21 K, with a much higher critical field > 5 T. Our observations are in strong contrast to previous reports of doping or pressurizing layered compounds AeFe₂As₂ (or Ae122), where Ae = Ca, Sr, or Ba. In Ae122, hole-doping has been previously observed to generate superconductivity with a transition temperature (Tc) only up to 38 K and pressurization has been reported to produce superconductivity with a Tc up to 30 K. The unusual 49 K phase detected will be discussed.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1112150108