Superconductors of SmFe1−xCoxAsO synthesized by mechanical alloying

Abstract The SmFe 1− x Co x AsO ( x  = 0 − 0.25) superconductors were synthesized by mechanical alloying (MA) and rapid sintering method with Co atoms doped into FeAs layers to replace the Fe sites. The phase purity and superconducting properties of the samples were characterized by X-ray diffraction, electrical resistivity, magnetic susceptibility and Hall coefficient. All the samples belong to the tetragonal ZrCuSiAs structure type with the grain size in 1–3 μm. The superconducting critical temperature T c of SmFe 0.9 Co 0.1 AsO was 12.5 K, and the structure/SDW transition was suppressed by Co doping. The negative Hall coefficient of SmFe 0.9 Co 0.1 AsO indicated the electron conduction in the sample. The charge carrier density is about 2 × 10 20  cm −3 at the temperature lower than 150 K, larger than that of SmFeAsO.