Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc=33 K)

We synthesized the new Fe-based superconductor K0.8Fe2Se2 single crystals. The obtained single crystal exhibited a sharp superconducting transition and the onset and zero-resistivity temperature were estimated to be 33 and 31.8 K, respectively. A high upper critical field of 192 T was obtained. The anisotropy of superconductivity of K0.8Fe2Se2 was similar to 3.6. Both the high upper critical field and comparably low anisotropy are advantageous for applications under a high magnetic field. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549702]