Superconductivity in Ba1 xSmxFFeAs and Eu1 xSmxFFeAs systems

We synthesized the samples Ba1 x Sm x FFeAs and Eu1 x Sm x FFeAs with ZrCuSiAs-type structure. These samples were characterized by resistivity and susceptibility. It is found that the substitution of rare earth metal for alkaline earth metal in the two systems suppresses the anomaly in resistivity and induces superconductivity. Superconductivity at 54 K in nominal composition Ba0.5Sm0.5FFeAs and at 51 K for Eu0.5Sm0.5FFeAs is realized, indicating that the superconducting transition temperatures in the iron arsenide fluorides is the same as that in oxypnictides with the same structure. Supported by the National Natural Science Foundation of China (Grant No. 10774135) and National Basic Research Program of China (Grant Nos. 2006CB601001, 2006CB922005)