Structural and transport properties of Sr2VO3−δ FeAs superconductors with different oxygen deficiencies
Sr2VO3−δFeAs superconductors with different oxygen deficiencies have been successfully fabricated. It is found that the superconducting transition temperature drops down monotonically with the increase of nominal oxygen deficiency. The diminishing of superconductivity is accompanied by the enhancement of residual resistivity, indicating an anomalous scattering effect induced by the oxygen deficiency. The highest superconducting transition temperature at about 36 K is achieved near the stoichiometrical sample Sr2VO2.9FeAs. The Hall effect measurements reveal that the density of charge carriers (electron-like here) varies qualitatively with the increase of nominal oxygen deficiency. Magnetotransport measurements show that the superconducting transition changes from one-step-like shape at low fields to two-step-like one at high fields, indicating an enhanced vortex motion due to the high anisotropy.