Superconductivity at 55 K in iron-based F-doped layered quaternary   compound Sm[O1-xFx]FeAs
  Here we report the superconductivity in the iron-based oxyarsenide Sm[O1-xFx]FeAs, with the onset resistivity transition temperature at 55.0 K and Meissner transition at 54.6 K. This compound has the same crystal structure as LaOFeAs with shrunk crystal lattices, and becomes the superconductor with the highest critical temperature among all materials besides copper oxides. 
Zhi-An Ren, Wei Lu, Jie Yang, Wei Yi, Xiao-Li Shen, Zheng-Cai Li,   Guang-Can Che, Xiao-Li Dong, Li-Ling Sun, Fang Zhou, Zho...