Preparation and Superconducting Properties of F-doped SmO_(1-x)F_xFeAs

摘要

Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFxFeAs compound.X-ray diffraction(XRD) results prove that the lattice parameters a and c decrease systematically with increasing x in between 00.35 the a and c increase with the decrease of x in the SmO1-xFxFeAs.The critical temperature(Tc) increases with increasing x in between 0.15≤x≤0.3,while x>0.3 the Tc decreases with the increase of x.It is found that at x=0.3 SmO0.7F0.3FeAs has the highest onset resistivity transition temperature of 55.5 K.The critical current density(Jc) value at 10 K for the obtained SmO0.7F0.3FeAs is 1.3×10 5 A/cm2(0T).Meanwhile one can estimates Hc2(0) from the slope of the Hc2(T) curve at T =Tc(HC2 is the upper critical field),and for the 90% normal-state resistivity(ρn) criterion(Tc=55 K),Hc2(0) is determined to be ～253 T.