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arXiv · 1106.2157

The Unusual Superconducting State at 49 K in Electron-Doped CaFe2As2 at Ambient

B. Lv·L. Z. Deng·M. Gooch·F. Y. Wei·Y. Y. Sun·J. Meen·Y. Y. Xue·B. Lorenz·C. W. Chu
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Abstract

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.

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B. Lv, L. Z. Deng, M. Gooch, F. Y. Wei, Y. Y. Sun, J. Meen, Y. Y. Xue, B. Lorenz, C. W. Chu. 2011-06-10. The Unusual Superconducting State at 49 K in Electron-Doped CaFe2As2 at Ambient. https://doi.org/10.1073/pnas.1112150108

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