Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO (Re = rare-earth metal) without fluorine dopingZhi-An Ren, Guang-Can Che, Xiao-Li Dong, Jie Yang, Wei Lu, Wei Yi, Xiao-Li Shen, Zheng-Cai Li, Li-Ling Sun, Fang Zhou and Zhong-Xian Zhao
National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences - P.O. Box 603, Beijing 100190, PRC
received 16 April 2008; accepted in final form 12 May 2008; published July 2008
published online 11 June 2008
Here we report a new class of superconductors prepared by high-pressure synthesis in the quaternary family ReFeAsO (Re = Sm, Nd, Pr, Ce, La) without fluorine doping. The onset superconducting critical temperature (Tc) in these compounds increases with the reduction of the Re atom size, and the highest Tc obtained so far is 55 K in SmFeAsO. For the NdFeAsO compound with different oxygen concentration a dome-shaped phase diagram was found.
74.10.+v - Occurrence, potential candidates.
74.70.-b - Superconducting materials.
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