F Over-doped on fabrication and superconductivity of the SmO1-xFδFeAs compound

Abstract

The onset resistivity transition temperature (Tc) is as high as 56.5K in the SmO0.7F0.3FeAs sample prepared by the two-step solid state reaction method. The Jc of the sample is 2.3×105A/cm2 (10K and 0T). The Tc of the fluorin over-doped SmO0.7F0.35FeAs and SmO0.7F0.4FeAs samples prepared by the two-step solid state reaction method at 1100°C for 20 hours are 56K and 55K, and the Jc are 1.9×105A/cm2 and 1.7×105A/cm2 (10K and 0T), respectively. The XRD results show that the lattice parameters a and c decrease systematically with increasing x between 0<x≤0.3, when x>0.3, the lattice parameters a and c increase with the decreasing of x in the SmO1-xFxFeAs. But the lattice parameters a and c decrease with modest increasing of δ in the SmO1-xFδFeAs(δ≥x) compound, the values of a=3.9233 Å, c=8.4768 Å in the SmO0.7F0.35FeAs sample is obtained. It is shown that the decrease of the lattice parameters results in an increase of Tc.