Study of Superconductivity of Fe-Doping DyBa<sub>2</sub>Cu<sub>3-X</sub>Fe<sub>x</sub>O<sub>7-δ</sub> Systems Using Positron Experiment

Abstract

The effect of Fe doping on the structure, local electron density and electronic transport properties of DyBa2Cu3-XFexO7-δ(x = 0.00- 0.30) superconductors have been investigated by X-ray diffraction (XRD), positron annihilation and other experimental methods. XRD results indicate that the compound undergoes an Orthorhombic–Tetragonal (O-T) phase transition at about x = 0.10. The electrical transport measurements show that the superconductivity was strongly suppressed by Fe doping, and the superconducting transition temperature decreases with the increase of Fe doping content. The results of local electron density calculated using positron annihilation data show that the local electron density of the systems is strongly changed by the Fe doping, and the local electron density vary noticeably at the range of O-T phase transition. From the results of local electron density and the superconductivity, it can be found that the superconducting transition temperature decreases with decreasing the local electron density. These investigations reveal that the crystal phase transition and the local electron density could strongly affect the superconductivity in the Fe doped DyBa2Cu3-XFexO7-δsystems.