Superconducting properties and pinning mechanism of filamentary (Sm,Gd,Dy)–Ba–Cu–O doped with Co

Abstract

In this work, the effect of cobalt (Co) doping on the superconducting properties of filamentary (Sm1/3Gd1/3Dy1/3)1.18Ba2.12Cu3.09−xCoxOy (SGD123, x = 0 − 1.20) superconductors was investigated using samples prepared using a solution spinning method. Its pinning mechanism was also examined. The Co-doped x = 5.0 × 10−4 and 1.0 × 10−3 samples obtained a Jc value higher than that of the pure sample, although the Tc value of the SGD123 filaments slightly decreased with increasing Co content. The anisotropic behavior of the field dependence of the transport Jc can hardly be confirmed for the pure sample. The superconductivity of the pure sample disappeared at an applied magnetic field approximately 12 T, at most. In contrast, Co-doped x = 1.0 × 10−3 sample showed the angular dependence of the transport Jc in an applied magnetic field. Furthermore, the Co-doped x = 1.0 × 10−3 sample rotated at 90° maintained a Jc value higher than 103 A cm−2 in a magnetic field up to 17.5 T. Co doping was effective in enhancing Jc at self-field and high magnetic field. In addition, we attempted to elucidate the pinning mechanism of Co on the Jc enhancement of the SGD123 filament using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy measurements.