Superconductivity at 57.3 K in La-doped iron-based layered compound Sm0.95La0.05O0.85F0.15FeAs

Here, we report the synthesis and super-conductivity of the La-doped iron-based compound Sm0.95La0.05O0.85F0.15FeAs; the resistivity and magnetic measurement indicate that the onset transition temperature as high as 57.3 K. This compound has the same crystal structure as ZrCuSiAs type tetragonal layered structure. The higher T (c) compares to SmO0.85F0.15FeAs was attributed to partly La-substitution.